Heat exchanger

ABSTRACT

Refrigerant tubes each having a refrigerant side turning portion for changing a flow direction of refrigerant, and cooling medium tubes each having a cooling medium side turning portion for changing a flow direction of coolant for an electric motor MG for travelling are alternately stacked over each other between a refrigerant header tank and a cooling medium header tank. An outer fin is disposed in an outside air passage formed between the refrigerant tube and the coolant tube adjacent to each other. The refrigerant side turning portion is positioned closer to the cooling medium header tank than the refrigerant header tank. The cooling medium side turning portion is positioned closer to the refrigerant side header tank than the cooling medium header tank.

CROSS REFERENCE TO RELATED APPLICATION

This application is based on and claims the benefit of priority ofJapanese Patent Applications No. 2010-251119 filed on Nov. 9, 2010, andNo. 2011-233083 filed on Oct. 24, 2011, the disclosures of which areincorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a compound heat exchanger that canexchange heat among three kinds of fluids.

BACKGROUND ART

Conventionally, compound heat exchangers have been conventionally known,which can exchange heat among three kinds of fluids. For example, PatentDocument 1 discloses a compound heat exchanger that can exchange heatbetween outdoor air (outside air) and a refrigerant of a refrigerationcycle device, and between the refrigerant and a coolant for cooling anengine.

Specifically, the heat exchanger disclosed in Patent Document 1 includesa plurality of linear refrigerant tubes laminated, each having both endsconnected to refrigerant tanks for collecting or distributing therefrigerant. The heat exchanger also includes heat pipes, each havingone end connected to a coolant tank for circulation of the coolant, anddisposed between the laminated refrigerant tubes in parallel to therefrigerant tubes. And, fins for promoting heat exchange are arranged inoutside air passages formed between the refrigerant tubes and the heatpipes.

The refrigeration cycle device disclosed in Patent Document 1 employssuch a compound heat exchanger as an evaporator for evaporatingrefrigerant by absorbing heat of the outside air and heat of the coolant(e.g., waste heat of an engine) in the refrigerant. At this time, thewaste heat of the engine transferred from the heat pipes can be used tosuppress frost formation of the heat exchanger.

RELATED ART DOCUMENTS Patent Document

-   [Patent Document 1]-   Japanese Unexamined Patent Publication No. 11-157326

In order to achieve the heat exchange between the refrigerant and theoutside air, and the heat exchange between the refrigerant and thecoolant as mentioned above in the heat exchanger of Patent Document 1,the refrigerant tank and the coolant tank are adjacent to each other inthe flow direction of the outside air, and the heat pipes are curvednear the coolant tank, so that the heat pipes are arranged between therefrigerant pipes extending linearly.

However, the arrangement of the refrigerant tank and the coolant tankadjacent to each other in the flow direction of the outside air leads toan increase in size of the entire heat exchanger in the flow directionof the outside air. Further, the heat exchanger of Patent Document 1 hasto use the complicated shaped heat pipes that curve near the coolanttank, thereby resulting in low productivity of the heat exchanger.

DISCLOSURE OF THE INVENTION

The present invention has been made in view of the above matters, and itis an object of the present invention to improve the productivity of aheat exchanger which can exchange heat among three kinds of fluids.

According to a first aspect of the present disclosure, a heat exchangerincludes: a first heat exchanging portion including a plurality of firsttubes through which a first fluid flows, and a first tank extending in adirection of lamination of the first tubes to collect or distribute thefirst fluid flowing through the first tubes, the first heat exchangingportion being adapted to exchange heat between the first fluid and athird fluid flowing around the first tubes; and a second heat exchangingportion including a plurality of second tubes through which a secondfluid flows, and a second tank extending in a direction of lamination ofthe second tubes to collect or distribute the second fluid flowingthrough the second tubes, the second heat exchanging portion beingadapted to exchange heat between the second fluid and the third fluidflowing around the second tubes. The first tubes and the second tubesare disposed between the first tank and the second tank, at least one ofthe first tubes is disposed between the second tubes, at least one ofthe second tubes is disposed between the first tubes, a space formedbetween the first tube and the second tube defines a third fluid passagethrough which the third fluid flows, and an outer fin is disposed in thethird fluid passage to promote heat exchange between both the heatexchanging portions while enabling heat transfer between the first fluidflowing through the first tubes and the second fluid flowing through thesecond tubes. In addition, the first tube is provided with a firstturning portion for changing a flow direction of the first fluid, thesecond tube is provided with a second turning portion for changing aflow direction of the second fluid, the first turning portion ispositioned closer to the second tank than the first tank, and the secondturning portion is positioned closer to the first tank than the secondtank.

Thus, the heat can be exchanged between the first fluid and the thirdfluid via the first tubes and the outer fins. The heat can also beexchanged between the second fluid and the third fluid via the secondtubes and the outer fins. The heat can further be exchanged between thefirst fluid and the second fluid via the outer fins. Accordingly, theheat exchange can be performed among three kinds of fluids.

The first and second tubes are disposed between the first and secondtanks, and the third fluid passage is formed in a space formed betweenthe first tube and the second tube, so that the first tank and thesecond tank are not arranged in the flow direction of the third fluid.Thus, the entire heat exchanger can be prevented from increasing in sizein the flow direction of the third fluid.

The first turning portion of the first tube is positioned closer to thesecond tank than the first tank, and the second turning portion of thesecond tube is positioned closer to the first tank than the second tank,so that the connection of the first tube to the first tank can have thesame or equivalent shape as the connection of the second tube to thesecond tank.

As a result, the heat exchanger of the present disclosure can improvethe productivity of the heat exchanger that can exchange heat amongthree kinds of fluids without increase in size. The term “three kinds offluids” as used herein means not only fluids with different propertiesor compositions, but also fluids which differ in temperature or state,such as a gas phase or a liquid phase, even when those fluids have thesame properties or components. Thus, the first to third fluids are notlimited to fluids with different properties or compositions.

According to a second aspect of the present disclosure, a temperature ofthe first fluid introduced into the first heat exchanging portion may bedifferent from a temperature of the second fluid introduced into thesecond heat exchanging portion, and the outer fin may be disposed in aspace formed between the first and second tubes and the other first andsecond tubes adjacent thereto.

When the first fluid introduced into the first heat exchanger differs intemperature from the second fluid introduced into the second heatexchanger, the thermal strain (amount of heat expansion) generated inthe first tube is different from that generated in the second tube,which might change the size of the first tube and second tube. In such acase, the outer fins promote the heat exchange between the respectivefluids, thereby reducing the difference in temperature between the firstfluid and the second fluid to relieve (reduce) the difference in thermalstrain between the first tube and the second tube. As a result, thebreakdown of the heat exchanger can be suppressed.

The term “spaces formed between the first and second tubes and the otherfirst and second tubes adjacent thereto” as used herein means spacesformed between a first tube and another first tube or a second tubeadjacent to the first tube, and between a second tube and a first tubeor another second tube adjacent to the second tube.

The term “introduction” or “flow out” as used herein means the movementof the refrigerant in the heat exchanger, and the term “inflow” or“outflow” as used herein means the movement of the refrigerant in eachtube.

According to a third aspect of the invention disclosed herein, each ofthe first tube and the second tube may be fixed to both the first tankand the second tank.

Since the first tube and the second tube are fixed to both the first andsecond tanks, the entire heat exchanger can have the mechanical strengthincreased. Further, the outer fin disposed in the third fluid passageprovided between the first tube and the second tube can be easily fixedfirmly.

According to a fourth aspect of the present disclosure, when one fluidwith a higher temperature, of the first fluid introduced into the firstheat exchanging portion and the second fluid introduced into the secondheat exchanging portion is defined as a high-temperature side fluid,when an upstream side portion of a high-temperature side tube of thefirst tube and the second tube through which the high-temperature fluidflows with respect to a corresponding one of the first and secondturning portions is defined as a high-temperature side tube upstreamportion, and when a downstream side portion of the high-temperature sidetube of the first tube and the second tube through which thehigh-temperature fluid flows with respect to the corresponding one ofthe first and second turning portions is defined as a high-temperatureside tube downstream portion, the temperature of the third fluid may belower than that of the high-temperature side fluid, and thehigh-temperature side tube upstream portion of at least one of thehigh-temperature side tubes may be positioned on an upstream side in aflow direction of the third fluid with respect to the high-temperatureside tube downstream portion.

Thus, the difference in temperature between the high-temperature sidefluid and the third fluid can be ensured on the upstream side of thefluid flow in the high-temperature side tube to increase the amount ofheat dissipation. As a result, the difference in temperature between thefirst fluid and the second fluid can be reduced to relieve thedifference in thermal strain between the first tubes and the secondtubes, and thereby it can suppress the breakdown of the heat exchanger.

According to a fifth aspect of the present disclosure, when one fluidhaving a lower temperature, of the first fluid introduced into the firstheat exchanging portion and the second fluid introduced into the secondheat exchanging portion is defined as a low-temperature side fluid, whenan upstream side portion of a low-temperature side tube of the firsttube and the second tube through which the low-temperature side fluidflows with respect to a corresponding one of the first and secondturning portions is defined as a low-temperature side tube upstreamportion, and when a downstream side portion of the low-temperature sidetube of the first tube and the second tube through which thelow-temperature fluid flows with respect to the corresponding one of thefirst and second turning portions is defined as a low-temperature sidetube downstream portion, the temperature of the third fluid may be lowerthan that of the low-temperature side fluid, and the low-temperatureside tube upstream portion of at least one of the low-temperature sidetubes may be positioned on the upstream side in the flow direction ofthe third fluid with respect to the low-temperature side tube downstreamportion.

Thus, on the upstream side of the fluid flow in the low-temperature sidetube, the difference in temperature between the low-temperature sidefluid and the third fluid can be ensured to increase the amount of heatdissipation. As a result, the difference in temperature between thefirst fluid and the second fluid can be reduced to relieve thedifference in thermal strain between the first tube and the second tube,which can suppress the breakdown of the heat exchanger.

According to a sixth aspect of the present disclosure, the temperatureof the third fluid may be lower than that of one fluid having a highertemperature, of the first fluid introduced into the first heatexchanging portion and the second fluid introduced into the second heatexchanging portion, and may be higher than that of the other fluidhaving a lower temperature.

Thus, the temperature of a high-temperature side fluid of the first andsecond fluids in the heat exchanger is decreased while the temperatureof a low-temperature side fluid is increased, and thereby it can reducethe difference in temperature between the first fluid and the secondfluid. As a result, the difference in thermal strain between therespective tubes can be relieved to effectively suppress the breakdownof the heat exchanger.

According to a seventh aspect of the present disclosure, when anupstream side portion of the first tube with respect to the firstturning portion is defined as a first tube upstream portion, when adownstream side portion of the first tube with respect to the firstturning portion is defined as a first tube downstream portion, when anupstream side portion of the second tube with respect to the secondturning portion is defined as a second tube upstream portion, and when adownstream side portion of the second tube with respect to the secondturning portion is defined as a second tube downstream portion, thefirst tube upstream portion and the second tube upstream portion may bearranged in a direction of lamination of the first and second tubes, andthe first tube downstream portion and the second tube downstream portionmay be arranged in the direction of lamination of the first and secondtubes.

Thus, the difference in temperature between the first fluid flowingthrough the first tube and the second fluid flowing through the secondtube can be reduced to relieve the difference in thermal strain betweenthe first tube and the second tube.

According to an eighth aspect of the present disclosure, the first tubeupstream portion and the second tube upstream portion may be positionedon the upstream side in the flow direction of the third fluid withrespect to the first tube downstream portion and the second tubedownstream portion.

When the first fluid introduced into the first heat exchanging portionand the second fluid introduced into the second heat exchanging portionhave the temperature higher than that of the third fluid, the differencein temperature between the first and third fluids and the difference intemperature between the second and third fluids can be ensured on theupstream side of the fluid flow of the first tube and on the upstreamside of the fluid flow of the second tube to thereby increase the amountof heat dissipation. As a result, the difference in thermal strainbetween the first tube and the second tube can be relieved to therebysuppress the breakdown of the heat exchanger.

According to a ninth aspect of the present disclosure, the first tubesmay include an upstream side first tube group in which the first fluidintroduced into the first heat exchanging portion flows, and adownstream side first tube group in which the first fluid flowing fromthe upstream side first tube group flows to cause the first fluid toflow out the first heat exchanging portion, the second tubes may includean upstream side second tube group in which the second fluid introducedinto the second heat exchanging portion flows, and a downstream sidesecond tube group in which the second fluid flowing from the upstreamside second tube group flows to cause the second fluid to flow out thesecond heat exchanging portion. In this case, the first tube upstreamportion and the second tube upstream portion of the upstream side firsttube group and the upstream side second tube group may be positioned onthe upstream side in the flow direction of the third fluid with respectto the first tube downstream portion and the second tube downstreamportion.

When the first fluid introduced into the first heat exchanging portionand the second fluid introduced into the second heat exchanging portionhave the temperature higher than that of the third fluid, the differencein temperature between the first and second fluids is reduced, while thedifferences in temperature between the first and third fluids andbetween the second and third fluids are ensured on the upstream sides offluid flows of the upstream side first and second tube groups. Thus, theamount of heat dissipation can be increased. As a result, the differencein thermal strain between the first tube and the second tube can berelieved to thereby suppress the breakdown of the heat exchanger.

According to a tenth aspect of the present disclosure, the first tubeupstream portion and the second tube upstream portion of the downstreamside first tube group and the downstream side second tube group may bepositioned on the downstream side in the flow direction of the thirdfluid with respect to the first tube downstream portion and the secondtube downstream portion.

When the first fluid introduced into the first heat exchanging portionand the second fluid introduced into the second heat exchanger have thetemperature higher than that of the third fluid, the heat contained inthe first fluid and the second fluid can be sufficiently dissipated intothe third fluid on the downstream sides of fluid flows of the downstreamside first and second tube groups. As a result, the performance of theheat exchanger can be improved.

According to an eleventh aspect of the present disclosure, the outer finmay be bonded to the first and second tubes, and may be provided with aplurality of slits for locally weakening rigidity of the outer fin.

Thus, when the difference in thermal strain between the first tube andthe second tube occurs, the slits of the outer fins can absorb thestress acting on each tube. Further, the slits provided in the outerfins can also suppress the breakdown of the heat exchanger within apartial range even with the difference in thermal strain between therespective tubes.

According to a twelfth aspect of the present disclosure, an area of arefrigerant passage of an intermediate part of at least one of the firstturning portion and the second turning portion may be larger than anarea of a fluid passage of each of a fluid inflow portion and a fluidoutflow portion of the one turning portion.

Thus, when the first fluid passes through the first turning portion, orwhen the second fluid passes through the second turning portion, theloss in pressure can be reduced.

According to a thirteenth aspect of the present disclosure, an inner finmay be disposed within at least one of the first tube and the secondtube, to promote the heat exchange between the first fluid or the secondfluid, and the third fluid. In this case, the inner fin may have an endprotruding into an internal space of the first turning portion or secondturning portion.

Thus, the end of each inner fin protrudes into the internal space of thefirst turning portion or second turning portion, thereby preventing thefailure of connection between the inner fins and the inner peripheralsurfaces of the first tube and the second tube.

According to a fourteenth aspect of the present disclosure, each of thefirst tube and the second tube may be made of a plate tube formed bybonding a pair of plates. Alternatively, according to a fifteenth aspectof the present disclosure, each of the first tube and the second tubemay be formed by bending a flat tube with a flat section in a directionperpendicular to the longitudinal direction of the tube.

BRIEF DESCRIPTION OF DRAWINGS

The above and other objects, structures, and advantages of the presentinvention will become apparent from the following detailed descriptionof the invention, when taken in conjunction with the accompanyingdrawings, which respectively show:

FIG. 1 is an entire configuration diagram showing refrigerant flow pathsof a heat pump cycle in a heating operation according to a firstembodiment;

FIG. 2 is an entire configuration diagram showing refrigerant flow pathsof the heat pump cycle in a defrosting operation in the firstembodiment;

FIG. 3 is an entire configuration diagram showing refrigerant flow pathsof the heat pump cycle in a waste heat recovering operation in the firstembodiment;

FIG. 4 is an entire configuration diagram showing refrigerant flow pathsof the heat pump cycle in a cooling operation in the first embodiment;

FIG. 5 is a perspective view of the contour of a heat exchanger in thefirst embodiment;

FIG. 6( a) is a front view of a tube for refrigerant (tube for a coolingmedium) in the first embodiment, and FIG. 6( b) is a side view of thetube for refrigerant in FIG. 6( a);

FIG. 7 is a cross-sectional view taken along the line VII-VII of FIG. 6(a);

FIG. 8 is a cross-sectional view taken along the line VIII-VIII of FIG.6( a);

FIG. 9 is a cross-sectional view taken along the line IX-IX of FIG. 6(a);

FIG. 10 is a schematic perspective view for explaining the flows ofrefrigerant and coolant in the heat exchanger of the first embodiment;

FIG. 11 is a schematic partially exploded perspective view of the heatexchanger in the first embodiment;

FIG. 12 is a perspective view of the contour of a heat exchangeraccording to a second embodiment;

FIG. 13 is a schematic perspective view for explaining the flows ofrefrigerant and coolant in the heat exchanger of the second embodiment;

FIG. 14 is a schematic partially-exploded perspective view of the heatexchanger in the second embodiment;

FIG. 15( a) is a front view of a tube for refrigerant (tube for acooling medium) of the heat exchanger according to a third embodiment,and FIG. 15( b) is a side view of the tube for refrigerant shown in FIG.15( a);

FIG. 16 is an entire configuration diagram showing refrigerant flowpaths of the heat pump cycle in a waste heat recovering operationaccording to a fourth embodiment;

FIG. 17 is a perspective view of the contour of a heat exchangeraccording to a fifth embodiment;

FIG. 18 is a schematic appearance perspective view for explaining theflows of refrigerant and coolant in the heat exchanger of the fifthembodiment;

FIGS. 19( a), 19(b), 19(c), and 19(d) are schematic cross-sectionalviews of heat exchangers in the longitudinal direction of header tanksaccording to other embodiments;

FIG. 20 is an explanatory diagram for explaining the influences ofdifferences in temperature between the refrigerant and coolant in eachtube due to differences in structure between respective heat exchangers;

FIG. 21 is a schematic partially perspective view of a heat exchangeraccording to another embodiment; and

FIGS. 22( a), 22(b), and 22(c) are explanatory diagrams for explainingouter fins according to another embodiment.

EMBODIMENTS FOR CARRYING OUT THE INVENTION

Embodiments of the invention will be described below based on theaccompanying drawings. The same or equivalent parts through thefollowing embodiments are indicated by the same reference characters inthe figures.

First Embodiment

Referring to FIGS. 1 to 11, a first embodiment of the present inventionwill be described below. In this embodiment, a heat exchanger 16 of theinvention is applied to a heat pump cycle 10 for adjusting thetemperature of air to be blown into the interior of a vehicle in avehicle air conditioner 1. FIGS. 1 to 4 are entire configurationdiagrams of the vehicle air conditioner 1 in this embodiment. Thevehicle air conditioner 1 is applied to the so-called hybrid car, whichcan obtain a driving force for traveling from an internal combustionengine (engine) and an electric motor MG for traveling.

The hybrid car can perform switching between a traveling state in whichthe vehicle travels obtaining the driving force from both engine andelectric motor MG for traveling by operating or stopping the engineaccording to a traveling load on the vehicle or the like, and anothertraveling state in which the vehicle travels obtaining the driving forceonly from the electric motor MG for traveling by stopping the engine.Thus, the hybrid car can improve the fuel efficiency as compared tonormal cars obtaining a driving force for traveling only from theengine.

The heat pump cycle 10 in the vehicle air conditioner 1 is anevaporation compression refrigeration cycle that serves to heat or coolthe air in the vehicle compartment to be blown into the vehicle interioras a space of interest for air conditioning. That is, the heat pumpcycle 10 can switch between refrigerant flow paths to thereby perform aheating operation (heater operation) and a cooling operation (cooleroperation). The heating operation is performed to heat the vehicleinterior by heating the air in the vehicle compartment as a fluid ofinterest for heat exchange. The cooling operation is performed to coolthe vehicle interior by cooling the air in the vehicle compartment.

Then, the heat pump cycle 10 can also perform a defrosting operation anda waste heat recovering operation. The defrosting operation is performedto melt and remove frost formed at an outdoor heat exchanging portion 60of the heat exchanger 16 in the heating operation by changing the flowrate of the refrigerant, coolant, or outside air flowing through theheat exchanger 16 as will be described later. The waste heat recoveringoperation is performed to absorb heat of the electric motor MG fortraveling in the refrigerant as the external heat source in the heatingoperation. In the entire configuration diagrams of the heat pump cycle10 shown in FIGS. 1 to 4, the flows of refrigerant in the respectiveoperations are designated by a solid arrow.

The heat pump cycle 10 of this embodiment employs a normal flon-basedrefrigerant as the refrigerant, and forms a subcritical refrigerationcycle whose high-pressure side refrigerant pressure does not exceed thecritical pressure of the refrigerant. Refrigerating machine oil forlubricating a compressor 11 is mixed into the refrigerant, and a part ofthe refrigerating machine oil circulates through the cycle together withthe refrigerant.

First, the compressor 11 is positioned in an engine room, and is tosuck, compress, and discharge the refrigerant in the heat pump cycle 10.The compressor is an electric compressor which drives a fixeddisplacement compressor 11 a having a fixed discharge capacity by use ofan electric motor 11 b. Specifically, various types of compressionmechanisms, such as a scroll type compression mechanism, or a vanecompression mechanism, can be employed as the fixed displacementcompressor 11 a.

The electric motor 11 b is one whose operation (number of revolutions)is controlled by a control signal output from an air conditioningcontroller to be described later. The motor 11 b may use either an ACmotor or a DC motor. The control of the number of revolutions of themotor changes a refrigerant discharge capacity of the compressor 11.Thus, in this embodiment, the electric motor 11 b serves as dischargecapacity changing means of the compressor 11.

A refrigerant discharge port of the compressor 11 is coupled to arefrigerant inlet side of an indoor condenser 12 as a user-side heatexchanger. The indoor condenser 12 is disposed in a casing 31 of anindoor air conditioning unit 30 of the air conditioner 1 for thevehicle. The indoor condenser is a heat exchanger for heating thatexchanges heat between a high-temperature and high-pressure refrigerantflowing therethrough and the air in the vehicle compartment havingpassed through an indoor evaporator 20 to be described later. Thedetailed structure of the indoor air conditioning unit 30 will bedescribed later.

A fixed throttle 13 for heating is coupled to a refrigerant outlet sideof the indoor condenser 12. The fixed throttle 13 serves asdecompression means for the heating operation that decompresses andexpands the refrigerant flowing from the indoor condenser 12 in theheating operation. The fixed throttle 13 for heating can use an orifice,a capillary tube, and the like. The outlet side of the fixed throttle 13for heating is coupled to the refrigerant inlet side of the outdoor heatexchanging portion 60 of the compound heat exchanger 16.

A bypass passage 14 for the fixed throttle is coupled to the refrigerantoutlet side of the indoor condenser 12. The bypass passage 14 causes arefrigerant flowing from the indoor condenser 12 to bypass the fixedthrottle 13 for heating and to guide the refrigerant into the outdoorheat exchanging portion 60 of the heat exchanger 16. An opening/closingvalve 15 a for opening and closing the bypass passage 14 for the fixedthrottle is disposed in the bypass passage 14 for the fixed throttle.The opening/closing valve 15 a is an electromagnetic valve whose openingand closing operations are controlled by a control voltage output fromthe air conditioning controller.

The loss in pressure caused when the refrigerant passes through theopening/closing valve 15 a is extremely small as compared to the loss inpressure caused when the refrigerant passes through the fixed throttle13. Thus, when the opening/closing valve 15 a is opened, the refrigerantflowing out of the indoor condenser 12 flows into the outdoor heatexchanging portion 60 of the heat exchanger 16 via the bypass passage 14for the fixed throttle. In contrast, when the opening/closing valve 15 ais closed, the refrigerant flows into the outdoor heat exchangingportion 60 of the heat exchanger 16 via the fixed throttle 13 forheating.

Thus, the opening/closing valve 15 a can switch between the refrigerantflow paths of the heat pump cycle 10. The opening/closing valve 15 a ofthis embodiment serves as refrigerant flow path switching means.Alternatively, as such a refrigerant flow path switching means, anelectric three-way valve or the like may be provided for switchingbetween a refrigerant circuit for coupling the outlet side of the indoorcondenser 12 to the inlet side of the fixed throttle 13 for heating, andanother refrigerant circuit for coupling the outlet side of the indoorcondenser 12 to the inlet side of the bypass passage 14 for the fixedthrottle.

The heat exchanger 16 is disposed in an engine room. The outdoor heatexchanging portion 60 of the heat exchanger 16 is a heat exchangingportion for exchanging heat between the low-pressure refrigerant flowingtherethrough and an outside air blown from a blower fan 17. Further, theoutdoor heat exchanging portion 60 serves as a heat exchanging portionfor evaporation that evaporates the low-pressure refrigerant to exhibita heat absorption effect in the heating operation, and also as a heatexchanging portion for heat dissipation that dissipates heat from thehigh-pressure refrigerant in the cooling operation.

The blower fan 17 is an electric blower whose operating ratio, that is,whose number of revolutions (volume of air) is controlled by a controlvoltage output from the air conditioning controller. The heat exchanger16 of this embodiment is integral with a radiator 70 for exchanging heatbetween the outside air blown from the blower fan 17 and the coolantcirculating through the above outdoor heat exchanging portion 60 and acoolant circulation circuit 40 for cooling the electric motor MG fortraveling.

The blower fan 17 of this embodiment serves as outdoor blowing means forblowing the outside air toward both the outdoor heat exchanging portion60 of the heat exchanger 16 and the radiator 70. The details structuresof the compound heat exchanger 16 including the coolant circulationcircuit 40, the outdoor heat exchanging portion 60, and the radiator 70which are integral with each other will be described in detail below.

The outlet side of the outdoor heat exchanging portion 60 of the heatexchanger 16 is coupled to an electric three-way valve 15 b. Thethree-way valve 15 b has its operation controlled by a control voltageoutput from the air conditioning controller. The three-way valve 15 bserves as the refrigerant flow path switching means together with theabove opening/closing valve 15 a.

More specifically, in the heating operation, the three-way valve 15 bperforms switching to the refrigerant flow path for coupling the outletside of the outdoor heat exchanger 19 to the inlet side of anaccumulator 18 to be described later. In contrast, in the coolingoperation, the three-way valve 15 b performs switching to therefrigerant flow path for coupling the outlet side of the outdoor heatexchanging portion 60 of the heat exchanger 16 to the inlet side of afixed throttle 19 for cooling. The fixed throttle 19 for cooling servesas decompression means for the cooling operation for decompressing andexpanding the refrigerant flowing from the outdoor heat exchangingportion 60 in the cooling operation. The fixed throttle 19 has the samebasic structure as that of the above fixed throttle 13 for heating.

The outlet side of the fixed throttle 19 for cooling is coupled to therefrigerant inlet side of the indoor evaporator 20. The indoorevaporator 20 is disposed on the upstream side of the air flow withrespect to the indoor condenser 12 in the casing 31 of the indoor airconditioning unit 30. The indoor evaporator 20 is a heat exchanger forcooling that exchanges heat between the air in the vehicle compartmentand the refrigerant flowing therethrough to thereby cool the air withinthe vehicle interior.

A refrigerant outlet side of the indoor evaporator 20 is coupled to aninlet side of the accumulator 18. The accumulator 18 is a gas-liquidseparator for the low-pressure side refrigerant that separates therefrigerant flowing thereinto into liquid and gas phases, and whichstores therein the excessive refrigerant within the cycle. A vapor-phaserefrigerant outlet of the accumulator 18 is coupled to a suction side ofthe compressor 11. Thus, the accumulator 18 serves to suppress thesuction of the liquid-phase refrigerant into the compressor 11 tothereby prevent the compression of the liquid in the compressor 11.

Next, the indoor air conditioning unit 30 will be described below. Theindoor air conditioning unit 30 is disposed inside a gauge board(instrument panel) at the forefront of the vehicle compartment. The unit30 accommodates in the casing 31 forming an outer envelope, a blower 32,the above-mentioned indoor condenser 12, and the indoor evaporator 20.

The casing 31 forms an air passage for flowing the air in the vehiclecompartment, blown into the vehicle interior. The casing 31 is formed ofresin (for example, polypropylene) having some degree of elasticity, andexcellent strength. An inside/outside air switch 33 for switchingbetween the air (inside air) in the vehicle interior and the outside airis disposed on the most upstream side of the vehicle-interior air flowin the casing 31.

The inside/outside air switch 33 is provided with the inside air inletfor introducing the inside air into the casing 31, and the outside airinlet for introducing the outside air thereinto. An inside/outside airswitching door is positioned inside the inside/outside air switch 33 tocontinuously adjust the opening areas of the inside air inlet and theoutside air inlet to thereby change the ratio of volume of the insideair to the outside air.

The blower 32 for blowing the air sucked via the inside/outside airswitch 33 into the vehicle interior is disposed on the downstream sideof the air flow of the inside/outside air switch 33. The blower 32 is anelectric blower which includes a centrifugal multiblade fan (siroccofan) driven by an electric motor, and whose number of revolutions(volume of air) is controlled by a control voltage output from the airconditioning controller.

The indoor evaporator 20 and the indoor condenser 12 are disposed on thedownstream side of the air flow of the blower 32 in that order withrespect to the flow of the air in the vehicle interior. In short, theindoor evaporator 20 is disposed on the upstream side in the flowdirection of the air in the vehicle compartment with respect to theindoor condenser 12.

An air mix door 34 is disposed on the downstream side of the air flow inthe indoor evaporator 20 and on the upstream side of the air flow in theindoor condenser 12. The air mix door 34 adjusts the rate of volume ofthe air passing through the indoor condenser 12 among the air havingpassed through the indoor evaporator 20. A mixing space 35 is providedon the downstream side of the air flow in the indoor condenser 12 so asto mix the air exchanging heat with the refrigerant and heated at theindoor condenser 12, and the air bypassing the indoor condenser 12 andnot heated.

Air outlets for blowing the conditioned air mixed in the mixing space35, into the vehicle interior as a space of interest to be cooled aredisposed on the most downstream side of the air flow in the casing 31.Specifically, the air outlets (not shown) include a face air outlet forblowing the conditioned air toward the upper body of a passenger in thevehicle compartment, a foot air outlet for blowing the conditioned airtoward the foot of the passenger, and a defroster air outlet for blowingthe conditioned air toward the inner side of a front glass of thevehicle.

The air mix door 34 adjusts the rate of volume of air passing throughthe indoor condenser 12 to thereby adjust the temperature of conditionedair mixed in the mixing space 35, thus controlling the temperature ofthe conditioned air blown from each air outlet. That is, the air mixdoor 34 serves as temperature adjustment means for adjusting thetemperature of the conditioned air blown into the vehicle interior.

In short, the air mix door 34 serves as heat exchanging amountadjustment means for adjusting the amount of heat to be exchangedbetween the air in the vehicle interior and the refrigerant dischargedfrom the compressor 11 in the indoor condenser 12 serving as theuser-side heat exchanger. The air mix door 34 is driven by a servo motor(not shown) whose operation is controlled based on the control signaloutput from the air conditioning controller.

The face air outlet, foot air outlet, and defroster air outlet have, atthe respective upstream sides of the air flows thereof, a face door foradjusting an opening area of the face air outlet, a foot door foradjusting an opening area of the foot air outlet, and a defroster doorfor adjusting an opening area of the defroster air outlet, respectively(all doors being not shown).

The face door, foot door, and defroster door serve as air outlet modeswitching means for switching among air outlet modes. The doors aredriven by a servo motor (not shown) whose operation is controlled basedon a control signal output from the air conditioning controller via alink mechanism or the like.

Next, the coolant circulation circuit 40 will be described below. Thecoolant circulation circuit 40 is a cooling medium circulation circuitfor cooling the electric motor MG for traveling by allowing the coolant(for example, ethylene glycol aqueous solution) as a cooling medium(heat medium) to circulate through a coolant passage formed in the aboveelectric motor MG for traveling, which is one of the vehicle-mounteddevices generating heat in operation.

The coolant circulation circuit 40 is provided with a coolant pump 41,an electric three-way valve 42, the radiator 70 of the compound heatexchanger 16, and a bypass passage 44 for allowing the coolant to flowbypassing the radiator 70.

The coolant pump 41 is an electric pump for squeezing the coolant into acoolant passage formed within the electric motor MG for traveling in thecoolant circulation circuit 40, and whose number of revolutions (flowrate) is controlled by a control signal output from the air conditioningcontroller. Thus, the coolant pump 41 serves as cooling capacityadjustment means for adjusting the cooling capacity by changing the flowrate of the coolant for cooling the electric motor MG for traveling.

The three-way valve 42 switches between a cooling medium circuit forflowing the coolant into a radiator 70 by connecting the inlet side ofthe coolant pump 41 to the outlet side of the radiator 70, and anothercooling medium circuit for flowing the coolant to bypass the radiator 70by connecting the inlet side of the coolant pump 41 to the outlet sideof the bypass passage 44. The three-way valve 42 whose operation iscontrolled by a control voltage output from the air conditioningcontroller serves as circuit switching means for switching between thecooling medium circuits.

That is, the coolant circulation circuit 40 of this embodiment canperform switching between one cooling medium circuit for circulation ofthe coolant from the coolant pump 41, to the electric motor MG fortravelling, the bypass passage 44, and the coolant pump 41 in that orderas illustrated by a dashed arrow of FIG. 1 or the like, and anothercooling medium circuit for circulation of the coolant from the coolantpump 41, to the electric motor MG for traveling, the radiator 70, andthe coolant pump 41 in that order as illustrated by a dashed arrow ofFIG. 2 or the like.

Thus, when the three-way valve 42 performs switching to the coolingmedium circuit for allowing the coolant to bypass the radiator 70 duringthe operation of the electric motor MG for traveling, the coolant hasits temperature increased without dissipating its heat into the radiator70. That is, when the three-way valve 42 performs switching to thecooling medium circuit for allowing the coolant to bypass the radiator70, the heat (heat generated) contained in the electric motor MG fortraveling is stored in the coolant.

In contrast, when the three-way valve 42 performs switching to thecooling medium circuit for allowing the coolant to pass through theradiator 70 during the operation of the electric motor MG for traveling,the coolant flows into the radiator 70 and then exchanges heat with theoutside air blown from the blower fan 17. The heat exchanger 16 of thisembodiment allows the coolant flowing into the radiator 70 to exchangeheat with not only the outside air, but also the refrigerant flowingthrough the outdoor heat exchanging portion 60.

Next, the compound heat exchanger 16 of this embodiment will bedescribed in detail using FIGS. 5 to 11. FIG. 5 shows a perspective viewof the contour of the heat exchanger 16 of this embodiment. FIG. 6( a)shows a front view of a tube 61 for refrigerant (tube 71 for a coolingmedium) of the outdoor heat exchanging portion 60 (radiator 70) in thefirst embodiment. FIG. 6( b) shows a side view of the tube of FIG. 6(a). FIG. 7 shows an enlarged cross-sectional view taken along the lineVII-VII of FIG. 6( a). FIG. 8 shows a cross-sectional view taken alongthe line VIII-VIII of FIG. 6( a). FIG. 9 shows an enlargedcross-sectional view taken along the line IX-IX of FIG. 6( a). FIG. 10shows a schematic perspective view for explaining the flows ofrefrigerant and coolant in the heat exchanger 16.

As shown in FIG. 5, the outdoor heat exchanging portion 60 and theradiator 70 of the heat exchanger 16 includes a plurality of tubes (61and 71) for flowing the refrigerant or coolant therethrough, and tanks(62 and 72) for collection and distribution disposed on the end side ofeach of the tubes in the longitudinal direction and adapted to collectand distribute the refrigerant or coolant flowing through the tubes,which forms the so-called tank and tube heat exchanger structure.

Specifically, the outdoor heat exchanging portion 60 includes aplurality of refrigerant tubes 61 for allowing the refrigerant as afirst fluid to flow therethrough, and a refrigerant side header tank 62extending in the lamination direction of the tubes 61 to collect ordistribute the refrigerant flowing through the refrigerant tubes 61. Theoutdoor heat exchanging portion 60 is a heat exchanging portion forexchanging heat between the refrigerant flowing through the tubes 61 andair (outside air blown from the blower fan 17) as a third fluid flowingthrough around the refrigerant tubes 61.

In contrast, the radiator 70 includes a plurality of cooling mediumtubes 71 for allowing the coolant as a second fluid to flowtherethrough, and a cooling medium side header tank 72 extending in thelamination direction of the tubes 71 to collect or distribute thecoolant flowing through the tubes 71. The radiator 70 is a heatexchanging portion for exchanging heat between the coolant flowingthrough the tubes 71 and air (outside air blown from the blower fan 17)flowing around the tubes 71.

In this embodiment as shown in FIGS. 6( a) and 6(b), each of therefrigerant tube 61 and the cooling medium tube 71 employs the so-calledplate tube which is formed by bonding a pair of plates 61 a and 61 b (71a and 71 b) with concave and convex portions on one surface of eachplate so as to align the center of one plate with that of the other. Theplates 61 a and 61 b (71 a and 71 b) are formed of metal with excellentheat conductivity (aluminum alloy in this embodiment).

The refrigerant tubes 61 and the cooling medium tubes 71 in thisembodiment have the same basic structure. FIGS. 6( a) and 6(b)illustrate the refrigerant tube 61 while components of the coolingmedium tube 71 corresponding to components of the refrigerant tube 61are indicated by respective reference numerals within parentheses.

As shown in FIG. 5, the refrigerant tubes 61 and the cooling mediumtubes 71 extend in the direction that connect the refrigerant sideheader tank 62 with the cooling medium side header tank 72 to bedescribed later, and are disposed between the refrigerant side headertank 62 and the cooling medium side header tank 72. In short, therefrigerant side header tank 62 is positioned on one end side of each ofthe refrigerant tube 61 and the cooling medium tube 71 in thelongitudinal direction. The cooling medium side header tank 72 ispositioned on the other end side of each of the refrigerant tube 61 andthe cooling medium tube 71 in the longitudinal direction.

Each of the refrigerant tube 61 and the cooling medium tube 71 has oneend in the longitudinal direction fixed to the refrigerant side headertank 62, and the other end in the longitudinal direction fixed to thecooling medium side header tank 72.

As shown in FIGS. 6( a) and 6(b), the refrigerant tube 61 extends in thelongitudinal direction of the refrigerant tube 61 (in the directionperpendicular to the flow direction of outside air blown from the blowerfan 17). As shown in the cross-sectional view of FIG. 7, refrigerantflow paths 61 c with a flat section are arranged in two lines in theflow direction A of the outside air blown from the blower fan 17. Thus,the outer surface of a part forming the refrigerant flow path 61 c ofthe refrigerant tubes 61 is a flat surface 61 d expanding in parallel tothe flow direction of the outside air blown from the blower fan 17.

As shown in the cross-sectional view of FIG. 8, the end of each of bothrefrigerant flow paths 61 c arranged in two lines on the refrigerantside header tank 62 side is externally opened at the end of therefrigerant tube 61. In this embodiment, the refrigerant side headertank 62 is placed on the opened end of the refrigerant flow path 61 c,so that both the refrigerant flow paths 61 c are in communication withthe internal space of the refrigerant side header tank 62.

In contrast, as shown in the cross-sectional view of FIG. 9, the otherend of each of both refrigerant flow paths 61 c arranged in two lines onthe cool medium side header tank 72 side is not externally opened to theoutside of the refrigerant tube 61, and the refrigerant flow paths 61 cin two lines are connected together by a refrigerant side turningportion 61 e. In this way, the internal space of the cooling medium sideheader tank 72 is not in communication with the refrigerant tube 61, sothat the two-lined refrigerant flow paths 61 c are in communication witheach other.

Thus, in the refrigerant tube 61 of this embodiment, the refrigerantside turning portion 61 e is positioned closer to the cooling mediumside header tank 72 than the refrigerant side header tank 62. Asindicated by the solid arrow of FIG. 10, the refrigerant flowing intoone of the refrigerant flow paths 61 c arranged in two lines from therefrigerant side header tank 62 has its flow direction reversed at therefrigerant side turning portion 61 e, and flows into the otherrefrigerant flow path 61 c to return to the refrigerant side header tank62.

An area of a refrigerant passage of the refrigerant side turning point61 e is larger than that of a refrigerant passage of the refrigerantflow path 61 c. That is, the area of the refrigerant passage of anintermediate part of the refrigerant side turning portion 61 e is largerthan that of each of a refrigerant inflow part and a refrigerant outflowpart of the refrigerant side turning portion 61 e connected to therefrigerant flow path 61 c. The refrigerant passage area is defined as asectional area perpendicular to the flow direction of the refrigerant.

An enlarging portion 61 f is provided for enlarging the refrigerantpassage area of the refrigerant flow path 61 c, on the other end of therefrigerant flow path 61 c of the refrigerant tube 61 opposite to therefrigerant side turning point 61 e. Both refrigerant flow paths 61 care in communication with the internal space of the refrigerant sideheader tank 62 via the enlarging portion 61 f. The enlarging portion 61f is formed to enlarge a surface area of the inside of the refrigeranttube 61 to thereby improve the pressure resistance.

An inner fin 65 for promoting the heat exchange between the refrigerantand the outside air blown from the blow fan 17 is disposed within therefrigerant flow path 61 c of the refrigerant tube 61. The inner fin 65is formed by bending a thin metal plate in a wave shape. As shown inFIGS. 8 and 9, the inner fin 65 has both ends in the longitudinaldirection protruding into the internal space of the enlarging portion 61f and the refrigerant side turning portion 61 e, respectively.

In the cooling medium tube 71, like the refrigerant tube 61, coolingmedium flow paths 71 c with a flat section are arranged in two lines inthe flow direction A of the outside air blown from the blower fan 17.Thus, the outer surface of a part forming the cooling medium flow path71 c of the cooling medium tube 71 is a flat surface 71 d expanding inparallel to the flow direction of the outside air blown from the blowerfan 17.

Each cooling medium flow path 71 c of the cooling medium tube 71 has oneend on the cooling medium side header tank 72 side in communication withthe internal space of the cooling medium side header tank 72. The otherends of both cooling medium flow paths 71 c on the refrigerant headertank 62 side are connected to the cooling medium side turning portion 71e having the same structure as that of the refrigerant side turningportion 61 e.

Thus, in the cooling medium tube 71, the cooling medium side turningportion 71 e is positioned closer to the refrigerant side header tank 62than the cooling medium side header tank 72. As indicated by the dashedarrow of FIG. 10, the refrigerant flowing into one of the cooling mediumflow paths 71 c arranged in two lines from the cooling medium sideheader tank 72 has its flow direction reversed at the cooling mediumside turning portion 71 e, and flows into the other refrigerant flowpath 71 c to return to the cooling medium side header tank 72.

An inner fin 75 for promoting the heat exchange between the coolant andthe outside air blown from the blow fan 17 is disposed within the coolmedium flow path 71 c of the cool medium tube 71. The inner fin 75 hasthe same structure as that of the inner fin 65 disposed in therefrigerant flow path 61 c. The inner fin 75 has both ends in thelongitudinal direction protruding into the internal space of theenlarging portion 71 f and the cooling medium side turning portion 71 e,respectively.

In the refrigerant tube 61 and the cooling medium tube 71, the flatsurfaces 61 d and 71 d of the outer surfaces of the tubes are laminatedin parallel with a predetermined distance therebetween. That is, therefrigerant tube 61 is disposed between the cooling medium tubes 71.Conversely, the cooling medium tube 71 is disposed between therefrigerant tubes 61.

A space formed between the refrigerant tube 61 and the cooling mediumtube 71 forms an outside air passage 16 a (third fluid passage) forallowing the outside air blown from the blower fan 17 to flowtherethrough.

In the outside air passage 16 a, an outer fin 50 is disposed inconnection with the flat surface 61 d of the refrigerant tube 61 and theflat surface 71 d of the cooling medium tube 71 which are opposed toeach other. The outer fin 50 can promote the heat exchange between theoutside air and the refrigerant in the outdoor heat exchanging portion60, and the heat exchange between the outside air and the coolant in theradiator 70. Further, the outer fins 50 enable heat transfer between therefrigerant flowing through the refrigerant tube 61 and the coolantflowing through the cooling medium tube 71.

The outer fin 50 for use is a corrugated fin formed by bending a thinmetal plate in a wave shape. In this embodiment, the outer fin 50 iscoupled to both the refrigerant tube 61 and the cooling medium tube 71,which enables the heat transfer between the refrigerant tube 61 and thecooling medium tube 71.

Next, the detailed structures of the refrigerant tube 61, the coolingmedium tube 71, the refrigerant side header tank 62, and the coolingmedium side header tank 72 will be described below with reference toFIG. 11. FIG. 11 shows a schematic partially exploded perspective viewof the heat exchanger 16. For easy understanding, FIG. 11 omits theillustration of the outer fin 50.

As shown in FIG. 11, each refrigerant tube 61 includes a refrigeranttube upstream portion 611 located on the upstream side of therefrigerant side turning portion 61 e, and a refrigerant tube downstreamportion 612 located on the downstream side of the refrigerant sideturning portion 61 e. That is, the refrigerant tube 61 of thisembodiment is composed of the refrigerant tube upstream portion 611, therefrigerant side turning portion 61 e, and the refrigerant tubedownstream portion 612. In the refrigerant tube 61 of this embodiment,the refrigerant tube upstream portion 611 is disposed on the downstreamside in the flow direction A of the outside air with respect to therefrigerant tube downstream portion 612.

In contrast, each cooling medium tube 71 includes a cooling medium tubeupstream portion 711 located on the upstream side of the cooling mediumside turning portion 71 e, and a cooling medium tube downstream portion712 located on the downstream side of the cooling medium side turningportion 71 e. That is, the cooling medium tube 71 of this embodiment iscomposed of the cooling medium tube upstream portion 711, the coolingmedium side turning portion 71 e, and the cooling medium tube downstreamportion 712. In the cooling medium tube 71 of this embodiment, thecooling medium tube upstream portion 711 is disposed on the upstreamside in the flow direction A of the outside air with respect to thecooling medium tube downstream portion 712.

The refrigerant tubes 61 and the cooling medium tubes 71 in thisembodiment are disposed such that the refrigerant tube upstream portions611 and the cooling medium tube downstream portions 712 are arranged inthe lamination direction of the tubes 61 and 71, and such that therefrigerant tube downstream portions 612 and the cooling medium tubeupstream portions 711 are arranged in the lamination direction of thetubes 61 and 71.

With this arrangement, the refrigerant flowing through the refrigeranttube 61 flows from the downstream side in the flow direction of theoutside air to the upstream side thereof, and the coolant flowingthrough the cooling medium tube 71 flows from the upstream side in theflow direction of the outside air to the downstream side thereof. Thus,in the refrigerant tubes 61 and the cooling medium tubes 71, the flowdirection of refrigerant flowing through the refrigerant tube 61 isopposite to that of the coolant flowing through the cooling medium tube71 with respect to the flow direction A of the outside air.

Next, the refrigerant side header tank 62 and the cooling medium sideheader tank 72 will be described later. The refrigerant side header tank62 has the same basic structure as that of the cooling medium sideheader tank 72. The refrigerant side header tank 62 includes arefrigerant side plate 63 to which both the refrigerant tubes 61 and thecooling medium tubes 71 are fixed, and a refrigerant side tank 64 fixedto the refrigerant side plate 63.

A part of the refrigerant side plate 63 corresponding to eachrefrigerant tube 61 is provided with a communication hole penetratingthe plate. The refrigerant tube 61 passes through the communicationhole. Thus, the refrigerant flow path 61 c of each refrigerant tube 61is in communication with the internal space of the refrigerant sideheader tank 62. The width of the part of the refrigerant tube 61inserted into the communication hole in the flow direction of theoutside air is shorter than that of the refrigerant flow path 61 c.

Similarly, a part of the refrigerant side plate 63 corresponding to eachcooling medium tube 71 is provided with a communication hole penetratingthe plate. The refrigerant tube 71 is inserted into the communicationhole, so that the hole is closed. The width of the part of the coolingmedium tube 71 inserted into the communication hole in the flowdirection of the outside air is shorter than that of the cooling mediumflow path 71 c.

The refrigerant side plate 63 is fixed to the refrigerant side tank 64to thereby form a concave portion 63 a for partitioning a space formedbetween the plate 63 and tank 64. The concave portion 63 a is providedover the entire area of the refrigerant side plate 63 in thelongitudinal direction.

The refrigerant side tank 64 is fixed to the refrigerant side plate 63to thereby form a collection space 62 a for collecting the refrigerantstherein, and a distribution space 62 b for distributing the refrigerant.Specifically, the refrigerant side tank 64 is formed by pressing a flatmetal plate into a double mountain (W-like) shape as viewed in thelongitudinal direction.

A center portion 64 a of the double mountain shape of the refrigerantside tank 64 is coupled to the concave portion 63 a of the refrigerantside plate 63, which partitions the internal space into the collectionspace 62 a and the distribution space 62 b. In this embodiment, thecollection space 62 a is disposed on the windward side in the flowdirection A of the outside air, and the distribution space 62 b isdisposed on the leeward side in the flow direction A of the outside air.

As mentioned above, the refrigerant tube 61 passes through thecommunication hole of the refrigerant side plate 63, so that therefrigerant flow paths 61 c (refrigerant tube downstream portion 612)disposed on the windward side in the flow direction A of the outside airare brought into communication with the collection space 62 a, while therefrigerant flow paths 61 c (refrigerant tube upstream portion 611)disposed on the leeward side in the flow direction A of the outside airare brought into communication with the distribution space 62 b.

As shown in FIG. 5, one end of the refrigerant side tank 64 in thelongitudinal direction is connected to a refrigerant introduction pipe64 b for introducing the refrigerant into the distribution space 62 b,and a refrigerant guiding pipe 64 c for guiding the refrigerant from thecollection space 62 a. The other end of the refrigerant side tank 64 inthe longitudinal direction is closed by a closing member.

Also, as shown in FIG. 11, the cooling medium side header tank 72 alsoincludes a cooling medium side plate 73 and a cooling medium side tank74. The cooling medium tube 71 passes through a communication holeprovided at the part of the cooling medium plate 73 corresponding to thecooling medium tube 71. The refrigerant tube 61 is inserted into anothercommunication hole provided at the part of the cooling medium plate 73corresponding to the refrigerant tube 61.

The cooling medium side tank 74 is fixed to the cooling medium sideplate 73, causing a concave portion 73 a of the cooling medium sideplate 73 to be coupled to a center portion 74 a in the double mountainshape of the cooling medium side tank 74, which partitions the internalspace into a collection space 72 a for collecting the refrigerantstherein, and a distribution space 72 b for distributing the refrigerant.In this embodiment, the distribution space 72 b is disposed on thewindward side in the flow direction A of the outside air, and thecollection space 72 a is disposed on the leeward side in the flowdirection A of the outside air.

As mentioned above, the cooling medium tube 71 passes through thecommunication hole of the cooling medium side plate 73, so that thecooling medium flow paths 71 c (cooling medium tube upstream portion711) disposed on the windward side in the flow direction A of theoutside air are brought into communication with the distribution space72 b, while the cooling medium flow paths 71 c (cooling medium tubedownstream portion 712) disposed on the leeward side in the flowdirection A of the outside air are brought into communication with thecollection space 72 a.

As shown in FIG. 5, one end of the cooling medium side tank 74 in thelongitudinal direction is connected to a cooling medium introductionpipe 74 b for introducing the cooling medium into the distribution space72 b, and a cooling medium guiding pipe 74 c for guiding and derivingthe cooling medium from the collection space 72 a. The other end of thecooling medium side header tank 72 in the longitudinal direction isclosed by a closing member.

Thus, in the heat exchanger 16 of this embodiment, as shown in theschematic perspective view of FIG. 10, the refrigerant introduced intothe distribution space 62 b of the refrigerant side header tank 62 viathe refrigerant introduction pipe 64 b flows into each refrigerant flowpath 61 c (refrigerant tube upstream portion 611) of one of therefrigerant tubes 61 in two lines disposed on the leeward side in theflow direction A of the outside air.

Then, the refrigerant flowing from each refrigerant flow path 61 cdisposed on the leeward side (refrigerant tube upstream portion 611)flows into the other refrigerant flow path 61 disposed on the windwardside (refrigerant tube downstream portion 612) via the refrigerant sideturning portion 61 e. Further, the refrigerants flowing from therefrigerant flow paths 61 c (refrigerant tube downstream portion 612)disposed on the windward side are collected into the collection space 62a of the refrigerant side header tank 62, and then derived from therefrigerant guiding pipe 64 c.

That is, in the heat exchanger 16 of this embodiment, the refrigerantflows and turns around from the refrigerant flow path 61 c on theleeward side of the refrigerant tube 61 (refrigerant tube upstreamportion 611) to the refrigerant side turning portion 61 e, and therefrigerant flow path 61 c on the windward side of the refrigerant tube61 (refrigerant tube downstream portion 612) in that order.

Likewise, the coolant flows and turns around from the cooling mediumflow path 71 c on the windward side of the cooling medium tube 71(cooling medium tube upstream portion 711) to the cooling medium sideturning portion 71 e, and the cooling medium flow path 71 c on theleeward side of the cooling medium tube 71 (cooling medium tubedownstream portion 712) in that order. Thus, the refrigerants flowingthrough the adjacent refrigerant tubes 61 have the flow directionopposite to that of the coolants flowing through the adjacent coolingmedium tubes 71 in the longitudinal direction of the tubes 61 and 71 andin the flow direction of the outside air (which is referred to as an“opposite flow structure”).

Components of the above inner fins 65 and 72, the refrigerant sideheader tank 62, the cooling medium side header tank 72, and the outerfin 50 are formed of the same metal as that of the plates 61 a, 61 b, 71a, and 71 b forming the refrigerant tube 61 and the cooling medium tube71.

Now, a manufacturing method of the heat exchanger 16 will be describedbelow. First, the refrigerant tubes 61, the cooling medium tubes 71, therefrigerant side header tank 62, and the cooling medium header tank 72are temporarily fixed (which is referred to as a “tube-tank temporaryfixing step”).

Specifically, in the refrigerant tube 61, the plates 61 a and 61 b areassembled such that the center of the one plate is aligned with that ofthe other with the inner fin 65 fitted to the refrigerant flow path 61c. A claw portion is formed in at least one of the upstream side and thedownstream side of the plate 61 in the flow direction of the outside air(in this embodiment, the entire area in the vertical direction). Theclaw portion is bent toward the plate 61 b.

In this embodiment, the plate 61 a includes claw portions 61 g formedbetween the refrigerant flow paths 61 c arranged in two lines, and theclaw portions are bent into through holes formed in the plate 61 b, sothat the plate 61 a is temporarily fixed to the plate 61 b. Likewise, inthe cooling medium tube 71, the plates 71 a and 71 b and the inner fin75 are temporarily fixed together.

In the refrigerant side header tank 62, the refrigerant side plate 63and the refrigerant tank 64 are combined by bending the claw portionsformed at the outer peripheral ends of the refrigerant side tank 64 overthe refrigerant plate 63, so that the plates 63 and 64 are temporarilyfixed. Also, in the cooling medium header tank 72, the cooling mediumside plate 73 and the cooling medium tank 74 are temporarily fixed.

The order of the temporary fixing of the refrigerant tube 61, thecooling medium tube 71, the refrigerant side header tank 62, and thecooling medium side header tank 72 is not limited to the above.

Then, the refrigerant tube 61 and the cooling medium tube 71 areinserted into the communication holes provided in the refrigerant sideplate 63 of the refrigerant header tank 62 and in the cooling mediumside plate 73 of the cooling medium side header tank 72, respectively.At this time, in this embodiment, the tubes are inserted such that thedistance between the edge of an opening of the correspondingcommunication hole and each of the turning portions 61 e and 71 e andthe enlarging portions 61 f and 71 f is 3 mm or less.

The outer fins 50 are inserted and temporarily fixed to the outside airpassages 16 a formed in the refrigerant tubes 61 and the cooling mediumtubes 71, and then the respective introduction/guiding pipes 64 b, 64 c,74 b, and 74 c are temporarily fixed (which is referred to as a “heatexchanger temporary fixing step”).

After fixing the heat exchanger 16 temporarily assembled with a wire jigor the like, the entire heat exchanger 16 is put and heated in a heatingfurnace. At this time, solder previously cladded to the surface of eachcomponent is melted, and the heat exchanger 16 is cooled until thesolder is solidified again. As a result, the respective components areintegrally soldered (which is referred to as a “heat exchanger bondingstep”). The above method can produce the heat exchanger including theoutdoor heat exchanging portion 60 and the radiator 70 which areintegral with each other.

As can be seen from the above description, the outdoor heat exchangingportion 60 of this embodiment corresponds to a first heat exchangingportion; the refrigerant tube 61 corresponds to a first tube; therefrigerant side header tank 62 corresponds to a first tank; and therefrigerant side turning portion 61 e corresponds to a first turningportion, for example.

The refrigerant tube upstream portion 611 of the cooling medium tube 61corresponds to a first tube upstream portion; and the refrigerant tubedownstream portion 612 corresponds to a first tube downstream portion,for example.

In contrast, the radiator 70 corresponds to a second heat exchanger; thecooling medium tube 71 corresponds to a second tube; the cooling mediumside header tank 72 corresponds to a second tank; and the cooling mediumside turning portion 71 e corresponds to a second turning portion, forexample.

The cooling medium tube upstream portion 711 of the cooling medium tube71 corresponds to a second tube upstream portion; and the cooling mediumtube downstream portion 712 corresponds to a second tube downstreamportion, for example.

Now, an electric control unit of this embodiment will be describedbelow. The air conditioning controller is comprised of the knownmicrocomputer including a CPU, an ROM, and an RAM, and peripheralcircuits thereof. The control unit controls the operation of each ofvarious types of air conditioning controller 11, 15 a, 15 b, 17, 41, and42 connected to its output by executing various operations andprocessing based on air conditioning control programs stored in the ROM.

A group of various sensors for control of air conditioning is coupled tothe input side of the air conditioning controller. The sensors includean inside air sensor for detecting a temperature of the vehicleinterior, an outside air sensor for detecting a temperature of theoutside air, a solar radiation sensor for detecting an amount of solarradiation in the vehicle interior, and an evaporator temperature sensorfor detecting a temperature of blown air from the indoor evaporator 20(evaporator temperature). And, the sensors also include a dischargedrefrigerant temperature sensor for detecting a temperature of therefrigerant discharged from the compressor 11, an outlet refrigeranttemperature sensor 51 for detecting a refrigerant temperature Te on theoutlet side of the outdoor heat exchanging portion 60, and a coolanttemperature sensor 52 serving as coolant temperature detection means fordetecting a coolant temperature Tw of the coolant flowing into theelectric motor MG for traveling.

In this embodiment, the coolant temperature sensor 52 detects thecoolant temperature Tw of the coolant squeezed from the coolant pump 41.Alternatively, the coolant temperature Tw of the coolant sucked into thecoolant pump 41 may be detected.

An operation panel (not shown) disposed near an instrument board at thefront of the vehicle compartment is connected to the input side of theair conditioning controller. Operation signals are input from varioustypes of air conditioning operation switches provided on the operationpanel. Various air conditioning operation switches provided on the panelinclude an operation switch for the air conditioner for the vehicle, avehicle-interior temperature setting switch for setting the temperatureof the vehicle interior, and a selection switch for selecting anoperation mode.

The air conditioning controller includes control means for controllingthe electric motor 11 b for the compressor 11, and the opening/closingvalve 15 a and the like which are integral with each other, and isdesigned to control the operations of these components. In the airconditioning controller of this embodiment, the structure (hardware andsoftware) for controlling the operation of the compressor 11 serves asrefrigerant discharge capacity control means. The structure forcontrolling the operations of the respective devices 15 a and 15 bforming the refrigerant flow path switching means serves as refrigerantflow path control means. The structure for controlling the operation ofthe three-way valve 42 forming the cooling medium circuit switchingmeans for coolant serves as cooling medium circuit control means.

The air conditioning controller of this embodiment includes thestructure (frost formation determination means) for determining whetheror not the frost is formed at the outdoor heat exchanger 60, based on adetection signal from the above sensor group for the air conditioningcontrol. Specifically, when the speed of a travelling vehicle is equalto or less than a predetermined reference value (in this embodiment, 20km/h), and the refrigerant temperature Te on the outlet side of theoutdoor heat exchanger 60 is equal to or less than 0° C., the frostformation determination means of this embodiment determines that thefrost formation is caused at the outdoor heat exchanger 60.

Next, the operation of the vehicle air conditioner 1 with the abovearrangement in this embodiment will be described below. The vehicle airconditioner 1 of this embodiment can execute a heating operation forheating the vehicle interior, and a cooling operation for cooling thevehicle interior. In the heating operation, a defrosting operation and awaste heat recovering operation can also be carried out. Now, eachoperation will be explained in the following.

(a) Heating Operation

The heating operation is started when the heating operation mode isselected by the selection switch with the operation switch of theoperation panel turned on (ON). Then, in the heating operation, when thefrost formation determination means determines that the frost is formedat the outdoor heat exchanger 60, the defrosting operation is performed.When the coolant temperature Tw detected by the coolant temperaturesensor 52 is equal to or more than the predetermined referencetemperature (in this embodiment, 60° C.), the waste heat recoveringoperation is performed.

In the normal heating operation, the air conditioning controller closesthe opening/closing valve 15 a, and switches the three-way valve 15 b tothe refrigerant flow path for coupling the outlet side of the outdoorheat exchanging portion 60 to the inlet side of the accumulator 18.Further, the controller actuates the coolant pump 41 to squeeze thecoolant in a predetermined flow rate, and switches the three-way valve42 of the coolant circulation circuit 40 to the cooling medium circuitfor allowing the coolant to bypass the radiator 70.

In this way, the heat pump cycle 10 is switched to the refrigerant flowpath for allowing the refrigerant to flow as illustrated by the solidarrow in FIG. 1. The coolant circulation circuit 40 is also switched tothe cooling medium circuit for allowing the refrigerant to flow asillustrated by the dashed arrow in FIG. 1.

The air conditioning controller with the above refrigerant flow path andcooling medium circuit reads a detection signal from the above sensorgroup for the air conditioning control and an operation signal from theoperation panel. Based on the detection signal and the operation signal,a target outlet air temperature TAO is calculated as the targettemperature of the air to be blown into the vehicle interior. Further,the operating states of various air conditioning control componentsconnected to the output side of the air conditioning controller aredetermined based on the calculated target outlet air temperature TAO andthe detection signal from the sensor group.

For example, the refrigerant discharge capacity of the compressor 11,that is, a control signal output to the electric motor of the compressor11 is determined as follows. First, a target evaporator outlet airtemperature TEO of the indoor evaporator 20 is determined based on thetarget outlet air temperature TAO with reference to a control mappreviously stored in the air conditioning controller.

Based on a deviation between the target evaporator outlet airtemperature TEO and the blown air temperature from the indoor evaporator20 detected by the evaporator temperature sensor, the control signal tobe output to the electrode motor of the compressor 11 is determined suchthat the blown air temperature of the air blown from the indoorevaporator 20 approaches the target evaporator outlet air temperatureTEO by use of a feedback control method.

The control signal to be output to the servo motor of the air mix door34 is determined based on the target outlet air temperature TAO, theblown air temperature of the indoor evaporator 20, and the temperatureof the refrigerant discharged from the compressor 11 detected by thedischarge refrigerant temperature sensor such that the temperature ofair blown into the vehicle interior becomes a desired temperature set bythe passenger using the vehicle interior temperature setting switch.

During the normal heating operation, the defrosting operation, and thewaste heat recovering operation, the opening degree of the air mix door34 may be controlled such that the whole volume of air in the vehicleinterior blown from the blower 32 passes through the indoor condenser12.

Then, the control signals determined as described above are output tovarious air conditioning control components. Thereafter, until thestopping of the vehicle air conditioner is requested by the operationpanel, a control routine is repeated at every predetermined controlcycle. The control routine includes a series of processes: reading ofthe detection signal and the operation signal, calculation of the targetoutlet air temperature TAO, determination of the operating states ofvarious air conditioning control components, and output of the controlvoltage and the control signal in that order. Such repetition of thecontrol routine is basically performed in other operation modes in thesame way.

In the heat pump cycle 10 during the normal heating operation, thehigh-pressure refrigerant discharged from the compressor 11 flows intothe indoor condenser 12. The refrigerant flowing into the indoorcondenser 12 exchanges heat with the vehicle interior air blown by theblower 32 through the indoor evaporator 20 to dissipate the heattherefrom, so that the air in the vehicle compartment is heated.

The high-pressure refrigerant flowing from the indoor condenser 12 flowsinto the fixed throttle 13 for heating to be decompressed and expandedby the throttle 13 because the opening/closing valve 15 a is closed. Thelow-pressure refrigerant decompressed and expanded by the fixed throttle13 for heating flows into an outdoor heat exchanging portion 60. Thelow-pressure refrigerant flowing into the outdoor heat exchangingportion 60 absorbs heat from the outside air blown by the blower fan 17,and is evaporated.

At this time, the coolant circulation circuit 40 is switched to thecooling medium circuit for allowing the coolant to bypass the radiator70, which prevents the coolant from dissipating heat to the refrigerantflowing through the outdoor heat exchanging portion 60, and alsoprevents the coolant from absorbing heat from the refrigerant flowingthrough the outdoor heat exchanging portion 60. That is, the coolantnever has a thermal influence on the refrigerant flowing through theoutdoor heat exchanging portion 60.

Since the three-way valve 15 b is switched to the refrigerant flow pathconnecting the outlet side of the outdoor heat exchanging portion 60 tothe inlet side of the accumulator 18, the refrigerant flowing from theoutdoor heat exchanging portion 60 flows into the accumulator 18 and isseparated into liquid and gas phases. The gas-phase refrigerantseparated by the accumulator 18 is sucked by the compressor 11 andcompressed again.

As mentioned above, in the normal heating operation, the air in thevehicle interior is heated by the indoor condenser 12 with the heatcontained in the refrigerant discharged from the compressor 11, whichcan perform the heating operation of the vehicle interior.

(b) Defrosting Operation

Next, the defrosting operation will be described below. In therefrigeration cycle device for evaporating the refrigerant by exchangingheat between the refrigerant and outside air in the outdoor heatexchanging portion 60, like the heat pump cycle 10 of this embodiment,when a refrigerant evaporation temperature of the outdoor heatexchanging portion 60 becomes equal to or less than a frost formationtemperature (specifically, 0° C.), the frost might be formed at theoutdoor heat exchanging portion 60.

Such formation of the frost closes the outside air passage 16 a of theheat exchanger 16 with the frost, which drastically reduces the heatexchange capacity of the outdoor heat exchanging portion 60. In the heatpump cycle 10 of this embodiment, when the frost formation is determinedto be caused at the outdoor heat exchanging portion 60 by the frostformation determination means in the heating operation, the defrostingoperation is started.

In the defrosting operation, the air conditioning controller stops theoperation of the compressor 11, and also stops the operation of theblower fan 17. Thus, during the defrosting operation, the flow rate ofrefrigerant flowing into the outdoor heat exchanging portion 60 isdecreased to thereby decrease the volume of outside air flowing into theoutside air passage 16 a, as compared to the normal heating operation.

The air conditioning controller switches the three-way valve 42 of thecoolant circulation circuit 40 to the cooling medium circuit forallowing the coolant to flow into the radiator 70 as indicated by thedashed arrow in FIG. 2. Thus, the coolant circulation circuit 40 isswitched to the cooling medium circuit for flowing the refrigerant asindicated by the dashed arrow in FIG. 2 without circulation of therefrigerant through the heat pump cycle 10.

Thus, the heat contained in the coolant flowing through the coolingmedium tubes 71 of the radiator 70 is transferred to the outdoor heatexchanging portion 60 via the outer fins 50, which performs thedefrosting operation of the outdoor heat exchanging portion 60. That is,the flow rates of the refrigerant and outside air flowing through theheat exchanger 16 are changed (specifically, reduced) to achieve thedefrosting operation effectively using the waste heat of the electricmotor MG for traveling.

(c) Waste Heat Recovering Operation

Next, the waste heat recovering operation will be described below.Preferably, in order to suppress overheat of the electric motor MG fortraveling, the temperature of the coolant is maintained at apredetermined upper limit temperature or less. Further, in order toreduce the friction loss due to an increase in viscosity of oil forlubrication sealed into the electric motor MG for traveling, preferably,the temperature of the coolant is maintained at a predetermined lowerlimit temperature or more.

In the heat pump cycle 10 of this embodiment, when the coolanttemperature Tw is equal to or more than the predetermined referencetemperature (60° C. in this embodiment) during the heating operation,the waste heat recovering operation is performed. In the defrostingoperation, the three-way valve 15 b of the heat pump cycle 10 isperformed in the same way as in the normal heating operation, but thethree-way valve 42 of the coolant circulation circuit 40 is switched tothe cooling medium circuit for flowing the coolant into the radiator 70as indicated by the dashed arrow in FIG. 3 in the same way as in thedefrosting operation.

Thus, as illustrated by the solid arrow in FIG. 3, the high-pressure andhigh-temperature refrigerant discharged from the compressor 11 heats theair in the vehicle interior at the indoor condenser 12, and is thendecompressed and expanded by the fixed throttle 13 for heating to flowinto the outdoor heat exchanging portion 60 in the same way as in thenormal heating operation.

Since the three-way valve 42 performs switching to the cooling mediumcircuit for flowing the coolant into the radiator 70, the low-pressurerefrigerant flowing into the outdoor heat exchanging portion 60 absorbsboth the heat contained in the outside air blown by the blower fan 17and the heat contained in the coolant and transmitted thereto via theouter fins 50, thereby to be evaporated. Other operations are the sameas those in the normal heating operation.

As described above, in the waste heat recovering operation, the air inthe vehicle interior is heated at the indoor condenser 12 with the heatof the refrigerant discharged from the compressor 11, which can performheating of the vehicle interior. At this time, the refrigerant absorbsnot only the heat contained in the outside air, but also the heatcontained in the coolant and transmitted thereto via the outer fins 50,which can achieve the heating of the vehicle interior effectively usingthe waste heat of the electric motor MG for traveling.

(d) Cooling Operation

The cooling operation is started when the cooling operation mode isselected by the selection switch with the operation switch of theoperation panel turned on (ON). In the cooling operation, the airconditioning controller opens the opening/closing valve 15 a, andswitches the three-way valve 15 b to the refrigerant flow path forconnecting the outlet side of the outdoor heat exchanging portion 60 tothe inlet side of the fixed throttle 19 for cooling. Thus, the heat pumpcycle 10 is switched to the refrigerant flow path for flowing therefrigerant as indicated by the solid arrow in FIG. 4.

At this time, when the coolant temperature Tw is equal to or more thanthe reference temperature, the three-way valve 42 of the coolantcirculation circuit 40 is switched to the cooling medium circuit forflowing the coolant into the radiator 70. In contrast, when the coolanttemperature Tw is less than the predetermined reference temperature, thethree-way valve 42 is switched to the cooling medium circuit forallowing the coolant to bypass the radiator 70. The flow of the coolantobtained when the coolant temperature Tw is equal to or more than thereference temperature is indicated by the dashed arrow in FIG. 4.

In the heat pump cycle 10 during the cooling operation, thehigh-pressure refrigerant discharged from the compressor 11 flows intothe indoor condenser 12, and exchanges heat with the air in the vehicleinterior blown by the blower 32 and having passed through the indoorevaporator 20 to dissipate heat therefrom. The high-pressure refrigerantflowing from the indoor condenser 12 flows into the outdoor heatexchanging portion 60 via the bypass passage 14 for the fixed throttlebecause the opening/closing valve 15 a is opened. The low-pressurerefrigerant flowing into the outdoor heat exchanging portion 60 furtherradiates heat toward the outside air blown by the blower fan 17.

Since the three-way valve 15 b is switched to the refrigerant flow pathfor connecting the outlet side of the outdoor heat exchanging portion 60to the inlet side of the fixed throttle 19 for cooling, the refrigerantflowing from the outdoor heat exchanging portion 60 is decompressed andexpanded by the fixed throttle 19 for cooling. The refrigerant flowingfrom the fixed throttle 19 for cooling flows into the indoor evaporator20, and absorbs heat from the air in the vehicle interior blown by theblower 32 to be evaporated. In this way, the air in the vehicle interiorcan be cooled.

The refrigerant flowing from the indoor evaporator 20 flows into theaccumulator 18, and is then separated into liquid and gas phases by theaccumulator 18. The gas-phase refrigerant separated by the accumulator18 is sucked into and compressed by the compressor 11 again. Asmentioned above, during the cooling operation, the low-pressurerefrigerant absorbs heat from the air in the vehicle interior andevaporates itself at the indoor evaporator 20 to thereby cool the air inthe vehicle compartment, which can perform cooling of the vehicleinterior.

As described above, the air conditioner 1 for the vehicle in thisembodiment can perform switching among the refrigerant flow paths of theheat pump cycle 10, and among the cooling medium circuits of the coolantcirculation circuit 40 to thereby carry out various operations. Further,in this embodiment, the above specific heat exchanger 16 can be used toperform appropriate heat exchange among three kinds of fluids, namely,refrigerant, coolant, and outside air in each operation.

More specifically, the heat exchanger 16 of this embodiment includesouter fins 50 each disposed in the outside air passage 16 a formedbetween the refrigerant tube 61 of the outdoor heat exchanging portion60 and the cooling medium tube 71 of the radiator 70. Such outer fins 50enable heat transfer between the refrigerant tubes 61 and the coolingmedium tubes 71.

Thus, during the defrosting operation, the heat contained in the coolantcan be transferred to the outdoor heat exchanging portion 60 via theouter fins 50, which can effectively use the waste heat of the electricmotor MG for traveling to defrost the outdoor heat exchanging portion60.

Further, in this embodiment, during the defrosting operation, theoperation of the compressor 11 is stopped to reduce the flow rate ofrefrigerant flowing into the outdoor heat exchanging portion 60, whichcan prevent the heat transferred to the outdoor heat exchanging portion60 from absorbing in the refrigerant flowing through the refrigeranttubes 61 via the outer fins 50 and the refrigerant tubes 61. That is,unnecessary heat exchange between the coolant and the refrigerant can besuppressed.

During the defrosting operation, the operation of the blower fan 17 isstopped to decrease the volume of outside air flowing into the outsideair passages 16 a, which can prevent the heat transmitted to the outdoorheat exchanging portion 60 via the outer fins 50 from being absorbed inthe outside air flowing through the outside air passages 16 a. That is,the unnecessary heat exchange between the coolant and outside air can besuppressed.

During the waste heat recovering operation, the heat exchanger exchangesheat between the coolant and the refrigerant via the refrigerant tubes61, the cooling medium tubes 71, and the outer fins 50, so that thewaste heat of the electric motor MG for traveling can be absorbed in therefrigerant. And the heat exchanger also exchanges heat between thecoolant and the outside air via the cooling medium tubes 71 and theouter fins 50, so that the unnecessary waste heat of the electric motorMG for traveling can be dissipated to the outside air.

During the normal heat operation, the heat exchanger exchanges heatbetween the refrigerant and the outside air via the refrigerant tubes 61and the outer fins 50, so that the heat of the outside air can beabsorbed in the refrigerant. And during the normal heat operation, thethree-way valve 42 of the coolant circulation circuit 40 is switched tothe cooling medium circuit for allowing the coolant to bypass theradiator 70, which can suppress the unnecessary heat exchange betweenthe coolant and outside air to store the waste heat of the electricmotor MG for traveling in the coolant, thus promoting the warming of theelectric motor MG for traveling.

In the heat exchanger 16 of this embodiment, the refrigerant tubes 61and the cooling medium tubes 71 are disposed between the refrigerantside header tank 62 and the cooling medium side header tank 72, so thateach outside air passage 16 a is formed of a space between therefrigerant tube 61 and the cooling medium tube 71. The refrigerant sideheader tank 62 and the cooling medium side header tank 72 are notarranged in the flow direction of the outside air. Thus, the entire heatexchanger 16 can be prevented from increasing in size in the flowdirection of the outside air.

Additionally, the refrigerant side turning portion 61 e of therefrigerant tube 61 is positioned closer to the cooling medium sideheader tank 72 than the refrigerant side header tank 62. And the coolingmedium side turning portion 71 e of the cooling medium tube 71 ispositioned closer to the refrigerant header tank 62 than the coolingmedium side header tank 72. The structure with the refrigerant sideheader tank 62 connected to the refrigerant tubes 61 can have the sameshape as that of the structure with the cooling medium side header tank72 connected to the cooling medium tube 71.

In this embodiment, the refrigerant side plate 63 of the refrigerantside header tank 62 and the cooling medium side plate 73 of the coolingmedium side header tank 72 are provided with communication holes incommunication with the refrigerant flow path 61 c and the cooling mediumflow path 71 c, respectively, and other closed communication holes. Thestructure for connecting the refrigerant tubes 61 to the refrigerantside header tank 62 can have the same shape as that for connecting thecooling medium tubes 71 to the cooling medium side header tank 72, whichcan improve the productivity of the heat exchanger.

As a result, the heat exchanger 16 of this embodiment can improve theproductivity of the heat exchanger that can exchange heat among threekinds of fluids without increase in size.

In the heat exchanger 16 of this embodiment, the refrigerant tube 61 andthe cooling medium tube 71 are fixed to both the refrigerant side headertank 62 and the cooling medium side header tank 72, which can increasethe mechanical strength of the entire heat exchanger 16. Further, in atemporary process of the outer fin 50 to be disposed in the outside airpassage 16 a, the outer fin 50 can be easily fixed temporarily, and thencan be strongly fixed after the temporary bonding.

The refrigerant passage area of an intermediate part of each of therefrigerant side turning portion 61 e and the cooling medium sideturning portion 71 e is larger than a fluid passage area of each of afluid inflow portion and a fluid outflow portion of the correspondingturning portion. When the refrigerant passes through the refrigerantside turning portion 61 e, or when the coolant passes through thecooling medium side turning portion 71 e, the loss in pressure can bereduced.

The ends of the inner fins 65 and 75 disposed inside the refrigeranttube 61 and the cooling medium tube 71 protrude into the internal spacesof the enlarging portions 61 f and 71 f of the respective turningportions 61 e and 71 e. Thus, the parts of the inner fins 65 and 75where the cladded solder is apt to be peeled off, such as the ends ofthe inner fins 65 and 75, do not serve as a surface of interest to besoldered, which tends to suppress the bonding defect between each of theinner fins 65 and 75 and the inner peripheral surface of each of therefrigerant tube 61 and the cooling medium tube 71.

Like this embodiment, in the heat exchanger 16 that can exchange heatamong three kinds of fluids, the temperature of refrigerant introducedinto the outdoor heat exchanging portion 60 sometimes differs from thatof coolant introduced into the radiator 70, depending on the operationcondition. In this case, the amount of thermal strain (heat expansionamount) generated in the refrigerant tube 61 differs from that generatedin the cooling medium tube 71, which might lead to a breakdown of theheat exchanger 16.

In contrast, the heat exchanger 16 of this embodiment includes the outerfins 50 disposed between the refrigerant tubes 61 and the cooling mediumtubes 71, which are alternately laminated or stacked at predeterminedintervals. Each outer fin 50 promotes the heat exchange among theoutside air, the refrigerant, and the coolant to thereby relieve thedifference in thermal strain between the tubes 61 and 71. Thus, the heatexchanger 16 of this embodiment can suppress the breakdown of therefrigerant tube 61 and the cooling medium tube 71 due to the differencein thermal strain (heat expansion amount) generated between therefrigerant tubes 61 and the cooling medium tubes 71.

In the heat exchanger 16 of this embodiment, the cooling medium tubeupstream portion 711 of the cooling medium tube 71 is located on theupstream side in the flow direction A of the outside air with respect tothe cooling medium tube downstream portion 712. Thus, in an operatingstate where the temperature of the cooling medium flowing into thecooling medium tube 71 is higher than the temperature of each of therefrigerant and outside air, the difference in temperature between thecoolant and the outside air can be ensured on the upstream side of thecoolant flow of the cooling medium tube 71 to thereby increase theamount of heat dissipation. As a result, the difference in temperaturebetween the coolant and the refrigerant can be reduced to relieve thedifference in thermal strain between the refrigerant tube 61 and thecooling medium tube 71. In this example, the coolant corresponds to the“high-temperature side fluid”; the cooling medium tube 71 to the“high-temperature side tube”; the cooling medium tube upstream portion711 of the cooling medium tube 71 to the “high-temperature side tubeupstream portion”; and the cooling medium tube downstream portion 712 ofthe cooling medium tube 71 to the “high-temperature side tube downstreamportion”. The refrigerant corresponds to the “low-temperature sidefluid”; the refrigerant tube 61 to the “low-temperature side tube”; therefrigerant tube upstream portion 611 of the refrigerant tube 61 to the“low-temperature side tube upstream portion”; and the refrigerant tubedownstream portion 612 of the refrigerant tube 61 to the“low-temperature side tube downstream portion”.

Second Embodiment

In this embodiment, some changes are made to the structure of the heatexchanger 16 of the first embodiment. The detailed structure of a heatexchanger 16 of this embodiment will be described below using FIGS. 12to 14.

FIG. 12 shows a perspective view of the contour of the heat exchanger 16in the first embodiment. FIG. 13 shows a schematic perspective view forexplaining the flows of refrigerant and coolant in the heat exchanger16. FIG. 14 shows a schematic partially exploded perspective view of theheat exchanger 16. FIGS. 12, 13, and 14 correspond to FIGS. 5, 10, and11 of the first embodiment, respectively. In FIGS. 12 to 14, the same orequivalent parts as those in the first embodiment are indicated by thesame reference characters. The same goes for all the following drawings.

As shown in FIGS. 12 and 14, each of the refrigerant tube 61 and thecooling medium tube 71 of this embodiment is formed by bending a flattube with a flat section in the direction perpendicular to thelongitudinal direction. More specifically, the refrigerant tube 61 isbent such that the flat surfaces thereof are opposed to each other, andthe cooling medium tube 71 is also bent such that the flat surfacesthereof are opposed to each other.

Thus, the refrigerant side turning portion 61 e of the refrigerant tube61 and the cooling medium side turning portion 71 e of the coolingmedium tube 71 in this embodiment are formed of the bent portions of thetubes 61 and 71, respectively. The outside air passages 16 a in thisembodiment are formed not only between the flat surface of therefrigerant tube 61 and the flat surface of the cooling medium tube 71opposed thereto, but also between the flat surfaces of the opposedrefrigerant tubes 61, and between the flat surfaces of the opposedcooling medium tubes 71.

The outside air passages 16 a are provided with the outer fins 50 whichare the same as in the first embodiment. FIG. 14 omits the illustrationof the outer fins 50 for easy understanding, like FIG. 11.

As shown in FIG. 14, the refrigerant tubes 61 are arranged in two linesalong the flow direction A of the outside air. An opening end of onerefrigerant tube 61 disposed on the leeward side is in communicationwith the distribution space 62 b of the refrigerant side header tank 62,while an opening end of the other tube 61 disposed on the windward sideis in communication with the collection space 62 a of the refrigerantside header tank 62.

A partition member (not shown) is disposed inside the refrigerant sideheader tank 62. The partition member causes the other opening end of theone refrigerant tube 61 disposed on the leeward side to be brought intocommunication with the other opening end of the other tube 61 disposedon the windward side without communicating with the collection space 62a and the distribution space 62 b inside the refrigerant side headertank 62.

As shown in FIG. 14, the cooling medium tubes 71 are arranged in twolines along the flow direction A of the outside air. An opening end ofone cooling medium tube 71 disposed on the windward side is incommunication with the distribution space 72 b of the cooling mediumside header tank 72, while an opening end of the other tube 71 disposedon the leeward is in communication with the collection space 72 a of thecooling medium side header tank 72.

A partition member (not shown) is also disposed inside the coolingmedium side header tank 72. The partition member causes the otheropening end of the one cooling medium tube 71 disposed on the windwardside to be brought into communication with the other opening end of theother tube 71 disposed on the leeward side without communicating withthe collection space 72 a and the distribution space 72 b inside thecooling medium side header tank 72.

Thus, as shown in FIG. 13, in the heat exchanger 16 of this embodiment,the refrigerant introduced into the distribution space 62 b of therefrigerant side header tank 62 flows into the refrigerant tube 61disposed on the leeward side to pass through the refrigerant sideturning portion 61 e of the refrigerant tube 61 disposed on the leewardside, and then returns to the refrigerant side header tank 62. Then, therefrigerant flows into the refrigerant tube 61 disposed on the windwardside to pass through the refrigerant side turning portion 61 e of therefrigerant side tube 61 disposed on the windward side, and is derivedfrom the collection space 62 a of the refrigerant side header tank 62.

In contrast, the refrigerant introduced into the distribution space 72 bof the cooling medium side header tank 72 flows into the cooling mediumtube 71 disposed on the windward side to pass through the cooling mediumside turning portion 71 e of the cooling medium tube 71 disposed on thewindward side, and then returns to the cooling medium side header tank72. Then, the refrigerant flows into the cooling medium tube 71 disposedon the leeward side to pass through the cooling medium side turningportion 71 e of the cooling medium side tube 71 disposed on the leewardside, and is derived from the collection space 72 a of the coolingmedium side header tank 72.

The structures and operations of other components of the heat pump cycle10 including the heat exchanger 16 are the same as those of the firstembodiment. Thus, like the first embodiment, the heat exchanger 16 ofthis embodiment can also perform the appropriate heat exchange amongthree kinds of fluids, refrigerant, coolant, and outside air in eachoperation of the heat pump cycle 10. This embodiment can also improvethe productivity of the heat exchanger that can exchange heat among thethree kinds of fluids without increase in size.

Further, the heat exchanger 16 of this embodiment uses as therefrigerant tube 61 and the cooling medium tube 71, the flat tube thatcan be formed at low cost by an extrusion process or drawing process.Therefore, this embodiment can further improve the productivity.

Third Embodiment

The second embodiment uses the flat tube bent with the flat surfaceparts opposed to each other, as the refrigerant tube 61 and the coolingmedium tube 71, by way of example. In this embodiment, as shown in FIG.15, each tube is bent such that a flat surface on the upstream side ofeach of the turning portions 61 e and 71 e and a flat surface on thedownstream side thereof are arranged in two lines on the same plane inthe flow direction A of the outside air.

In FIG. 15, (a) is a front view of the refrigerant tube 61 of thisembodiment (cooling medium tube 71), and (b) is a side view of the tubefor refrigerant. FIGS. 15( a) and 15(b) correspond to FIGS. 6( a) and6(b) of the first embodiment. FIGS. 15( a) and 15(b) shows therefrigerant tube 61, while components of the cooling medium tube 71corresponding to the components of the refrigerant tube 61 are indicatedby respective reference numerals within parentheses.

The structures and operations of other components of the heat pump cycle10 including the heat exchanger 16 are the same as those of the firstembodiment. Thus, like the first embodiment, the heat exchanger 16 ofthis embodiment can also perform the appropriate heat exchange amongthree kinds of fluids, refrigerant, coolant, and outside air in eachoperation of the heat pump cycle 10. This embodiment can also improvethe productivity of the heat exchanger that can exchange heat among thethree kinds of fluids without increase in size.

Like the second embodiment, this embodiment can also manufacture therefrigerant tube 61 and the cooling medium tube 71 at low cost, and thuscan further improve the productivity.

Fourth Embodiment

In this embodiment, as shown in the entire configuration diagram of FIG.16, some changes are made to the structure of the heat pump cycle 10 ofthe first embodiment. FIG. 16 shows the entire configuration diagram ofrefrigerant flow paths in the waste heat recovering operation in thisembodiment. In the figure, the flow of refrigerant in the heat pumpcycle 10 is indicated by a solid line, and the flow of coolant in thecoolant circulation circuit 40 is indicated by a dashed arrow.

Specifically, in this embodiment, the indoor condenser 12 of the firstembodiment is removed, and the compound heat exchanger 16 of the firstembodiment is disposed in the casing 31 of the indoor air conditioningunit 30. The outdoor heat exchanging portion 60 of the first embodimentin the compound heat exchanger 16 serves as the indoor condenser 12. Inthe following, a portion of the heat exchanger 16 serving as the indoorcondenser 12 is referred to as an “indoor condenser”.

In contrast, the outdoor heat exchanging portion 60 is composed of asingle heat exchanger for exchanging heat between the refrigerantflowing therethrough and the outside air blown by the blower fan 17. Thestructures of other components in this embodiment are the same as thoseof the first embodiment. In this embodiment, the defrosting operation isnot performed, but other operations are performed in the same way as thefirst embodiment.

Thus, during the waste heat recovering operation in this embodiment, theair in the vehicle interior is heated by exchanging heat with therefrigerant discharged from the compressor 11 in the indoor evaporatorof the heat exchanger 16. Further, the air in the vehicle interiorheated by the indoor condenser can be heated by exchanging heat withcoolant in the radiator 70 of the heat exchanger 16.

The structure of the heat pump cycle 10 of this embodiment can exchangeheat between the air in the vehicle interior and the coolant. Even whenthe operation of the heat pump cycle 10 (specifically, compressor 11) isstopped, the heating of the vehicle interior can be achieved. Even whenthe temperature of the refrigerant discharged from the compressor 11 islow and the heating capacity of the heat pump cycle 10 is low, theheating of the vehicle interior can be achieved.

Obviously, the heat exchanger 16 disclosed in the second and thirdembodiments may be applied to the heat pump cycle 10 of this embodiment.

Fifth Embodiment

In this embodiment, some changes are made to the structure of the heatexchanger 16 of the first embodiment. The detailed structure of a heatexchanger 16 of this embodiment will be described below using FIGS. 17and 18.

FIG. 18 shows a perspective view of the contour of the heat exchanger 16in this embodiment. FIG. 18 is a schematic perspective view forexplaining the flows of refrigerant and coolant in the heat exchanger16. FIGS. 17 and 18 correspond to FIGS. 5 and 10 of the firstembodiment. For convenience of the description, FIG. 17 omits theillustration of the tubes 61 and 71 and the outer fins 50 of the heatexchanger 16.

The outdoor heat exchanging portion 60 of the heat exchanger 16 in thisembodiment includes a refrigerant side header tank 62 composed of tanks621 and 622 arranged in two lines along the flow direction A of theoutside air. The first refrigerant tank 621 disposed on the upstreamside in the flow direction of the outside air of the tanks 621 and 622in two lines is provided with a partition member 621 c disposed in thecenter in the longitudinal direction for partitioning the internal spaceinto two spaces 621 a and 621 b.

The first refrigerant tank 621 is connected to tubes disposed on thewindward side in the flow direction A of the outside air among aplurality of refrigerant tube upstream portions 611 and refrigerant tubedownstream portions 612. The tank 621 serves as a collection anddistribution tank for collecting and/or distributing the refrigerantsflowing through the tubes.

One end of the first refrigerant tank 621 in the longitudinal directionis connected to the refrigerant introduction pipe 64 b for introducingthe refrigerant, and the other end of the refrigerant side tank 64 inthe longitudinal direction is connected to the refrigerant guiding pipe64 c for deriving and guiding the refrigerant. The refrigerantintroduction pipe 64 b is in communication with the distribution space621 a of the two spaces 621 a and 621 b formed in the first refrigeranttank 621. The refrigerant guiding pipe 64 c is in communication with thecollection space 621 b of the two spaces 621 a and 621 b formed in thefirst refrigerant tank 621.

Among the tanks 621 and 622 arranged in two lines and included in therefrigerant side header tank 62, the second refrigerant tank 622disposed on the downstream side in the flow direction A of the outsideair is connected to the tubes disposed on the leeward side in the flowdirection A of the outside air among the plurality of refrigerant tubeupstream portions 611 and the refrigerant tube downstream portions 612.The second refrigerant tank 622 serves as a collection and distributiontank for collecting and/or distributing the refrigerants flowing throughthe tubes. Both ends of the second refrigerant tank 622 in thelongitudinal direction are closed by closing members.

A group of the refrigerant tubes 61 for flowing therethrough therefrigerant introduced into the outdoor heat exchanging portion 60 viathe refrigerant introduction pipe 64 b forms an upstream siderefrigerant tube group 60 a. Another group of the refrigerant tubes 61for flowing therethrough the refrigerant from the upstream siderefrigerant tube group 60 a to derive the refrigerant from therefrigerant guiding pipe 64 c forms a downstream side refrigerant tubegroup 60 b.

In the refrigerant tubes 61 forming the upstream side refrigerant tubegroup 60 a, the refrigerant tube upstream portion 611 is disposed on theupstream side in the flow direction A of the outside air with respect tothe refrigerant tube downstream portion 612. In the refrigerant tubes 61forming the downstream side refrigerant tube group 60 b, the refrigeranttube upstream portion 611 is disposed on the downstream side in the flowdirection A of the outside air with respect to the refrigerant tubedownstream portion 612.

In the outdoor heat exchanging portion 60 of this embodiment, asindicated by a solid arrow in the schematic perspective view of FIG. 18,the refrigerant introduced into the distribution space 621 a of thefirst refrigerant tank 621 of the header tank 62 via the refrigerantintroduction pipe 64 b flows from the refrigerant tube upstream portion611 on the windward side in the outside air flow direction A in theupstream side refrigerant tube group 60 a to the refrigerant sideturning portion 61 e. The refrigerant then flows and turns around to therefrigerant tube downstream portion 612 on the leeward side in theoutside air flow direction A in the upstream side refrigerant tube group60 a. The refrigerant flowing from the refrigerant tube downstreamportion 612 into the second refrigerant tank 622 flows and turns aroundfrom the refrigerant tube upstream portion 611 on the leeward side inthe flow direction A of the outside air in the downstream siderefrigerant tube group 60 b to the refrigerant side turning portion 61e, and the refrigerant tube downstream portion 612 on the windword sidein the outside air flow direction A in the downstream side refrigeranttube group 60 b in that order.

Turning back to FIG. 17, the radiator 70 of the heat exchanger 16 ofthis embodiment includes the cooling medium side header tank 72 composedof tanks 721 and 722 arranged in two lines along the flow direction A ofthe outside air. The first cooling medium tank 721 disposed on theupstream side in the flow direction of the outside air of the tanks 721and 722 in two lines is provided with a partition member 721 c disposedin the center in the longitudinal direction for partitioning theinternal space into two spaces.

The first cooling medium tank 721 is connected to tubes disposed on thewindward side in the flow direction A of the outside air among aplurality of the cooling medium tube upstream portions 711 and thecooling medium tube downstream portions 712. The tank 721 serves as acollection and distribution tank for collecting and/or distributing therefrigerants flowing through the tubes.

One end of the first cooling medium tank 721 in the longitudinaldirection is connected to the cooling medium introduction pipe 74 b forintroducing the cooling medium, and the other end of the cooling mediumside tank 74 in the longitudinal direction is connected to the coolingmedium guiding pipe 74 c for deriving and guiding the cooling medium.The cooling medium introduction pipe 74 b is in communication with thedistribution space 721 a of the two spaces 721 a and 721 b formed in thefirst cooling medium tank 721. The cooling medium guiding pipe 74 c isin communication with the collection space 721 b of the two spaces 721 aand 721 b formed in the first cooling medium tank 721.

Among the tanks 721 and 722 arranged in two lines and included in thecooling medium side header tank 72, the second cooling medium tank 722disposed on the downstream side in the flow direction A of the outsideair is connected to the tubes disposed on the leeward side in the flowdirection A of the outside air among the cooling medium tube upstreamportions 711 and the cooling medium tube downstream portions 712. Thesecond cooling medium tank serves as a collection and distribution tankfor collecting and/or distributing the cooling medium flowing throughthe tubes. Both ends of the second cooling medium tank 722 in thelongitudinal direction are closed by closing members.

A group of the cooling medium tubes 71 for flowing therethrough thecoolant introduced into the radiator 70 via the cooling mediumintroduction pipe 74 b forms an upstream side cooling medium tube group70 a. Another group of the cooling medium tubes 71 for flowingtherethrough the coolant from the upstream side cooling medium tubegroup 70 a to derive the coolant from the cooling medium guiding pipe 74c forms a downstream side cooling medium tube group 70 b.

In the cooling medium tubes 71 forming the upstream side cooling mediumtube group 70 a, the cooling medium tube upstream portion 711 is placedon the upstream side in the flow direction A of the outside air withrespect to the cooling medium tube downstream portion 712. In thecooling medium tubes 71 forming the downstream side cooling medium tubegroup 70 b, the cooling medium tube upstream portion 711 is placed onthe downstream side in the flow direction A of the outside air withrespect to the cooling medium tube downstream portion 712.

In the radiator 70 of this embodiment, as indicated by a chain arrow inthe schematic perspective view of FIG. 18, the refrigerant introducedinto the distribution space 721 a of the first cooling medium tank 721of the cooling medium side header tank 72 via the refrigerant 64 b flowsfrom the cooling medium tube upstream portion 711 on the windward sidein the flow direction A of the outside air in the upstream side coolingmedium tube group 70 a to the cooling medium side turning portion 71 e.Then, the refrigerant flows and turns around to the cooling medium tubedownstream side 712 on the leeward side in the outside air flowdirection in the upstream side cooling medium tube group 70 a. Therefrigerant flowing from the cooling medium tube downstream portion 712into the second cooling medium tank portion 722 flows from the coolingmedium tube upstream portion 711 on the leeward side in the outside airflow direction A in the downstream side cooling medium tube group 70 bto the cooling medium side turning portion 71 e. Then, the refrigerantflows and turns around to the cooling medium tube downstream portion 712on the windward side in the flow direction A of the outside air in thedownstream side cooling medium tube group 70 b.

In the heat exchanger 16 of this embodiment, the refrigerant tubeupstream portion 611 of the upstream side refrigerant tube group 60 aand the cooling medium tube upstream portion 711 of the upstream sidecooling medium tube group 70 a are arranged in parallel in thelamination direction of the tubes 61 and 71. And, the refrigerant tubedownstream portion 612 of the upstream side refrigerant tube group 60 aand the cooling medium tube downstream portion 712 of the upstream sidecooling medium tube group 70 a are arranged in parallel in thelamination direction of the tubes 61 and 71.

In the heat exchanger 16 of this embodiment, the refrigerant tubeupstream portion 611 of the downstream side refrigerant tube group 60 band the cooling medium tube upstream portion 711 of the downstream sidecooling medium tube group 70 b are arranged in parallel in thelamination direction of the tubes 61 and 71. And, the refrigerant tubedownstream portion 612 of the downstream side refrigerant tube group 60b and the cooling medium tube downstream portion 712 of the downstreamside cooling medium tube group 70 b are arranged in parallel in thelamination direction of the tubes 61 and 71.

In the outdoor heat exchanging portion 60, the refrigerant flows fromthe downstream side to the upstream side in the flow direction of theoutside air in the upstream side refrigerant tube group 60 a, and therefrigerant flows from the downstream side to the upstream side in theflow direction of the outside air in the downstream side refrigeranttube group 60 b. Likewise, in the radiator 70, the coolant flows fromthe upstream side to the downstream side in the flow direction of theoutside air in the upstream side cooling medium tube group 70 a, andflows from the downstream side to the upstream side in the flowdirection of the outside air in the downstream side cooling medium tubegroup 70 b.

Thus, the refrigerant tubes 61 and the cooling medium tubes 71 formingthe upstream side refrigerant tube group 60 a and the upstream sidecooling medium tube group 70 a are designed to allow the refrigerants toflow in the same direction from the windward side to the leeward sidealong the flow direction A of the outside air. The refrigerant tubes 61and the cooling medium tubes 71 forming the downstream side refrigeranttube group 60 b and the downstream side cooling medium tube 70 b,respectively, are designed to allow the refrigerant and the coolant toflow in the same direction from the leeward side to the windward side inthe flow direction A of the outside air.

The structures and operations of other components of the heat pump cycle10 including the heat exchanger 16 are the same as those of the firstembodiment. Like the first embodiment, the heat exchanger 16 of thisembodiment can also perform appropriate heat exchange among three kindsof fluids, including refrigerant, coolant, and outside air in eachoperation of the heat pump cycle 10. This embodiment can also improvethe productivity of the heat exchanger that can exchange heat among thethree kinds of fluids without increase in size.

Additionally, in the heat exchanger 16 of this embodiment, therefrigerant tube upstream portion 611 of each refrigerant tube 61forming the upstream side refrigerant tube group 60 a is disposed on theupstream side in the flow direction A of the outside air with respect tothe refrigerant tube downstream portion 612. And, the cooling mediumtube upstream portion 711 of each cooling medium tube 71 forming theupstream side cooling medium tube group 70 a is disposed on the upstreamside in the flow direction A of the outside air with respect to thecooling medium tube downstream portion 712.

In the operating state in which the refrigerant introduced into theoutdoor heat exchanging portion 60 and the cooling medium introducedinto the radiator 70 have the temperature higher than that of theoutside air, a difference in temperature between the refrigerant andcoolant is reduced on the refrigerant upstream side of the upstream siderefrigerant tube group 60 a and on the coolant upstream side of theupstream side cooling medium tube group 70 a. And differences intemperature between the refrigerant and outside air and between thecooling medium and outside air can be ensured, which can increase theamount of heat dissipation. As a result, a difference in thermal strainbetween the refrigerant tube 61 and the cooling medium tube 71 can berelieved.

In the heat exchanger 16 of this embodiment, the refrigerant tubeupstream portion 611 of each refrigerant tube 61 forming the downstreamside refrigerant tube group 60 b is disposed on the downstream side inthe flow direction A of the outside air with respect to the refrigeranttube downstream portion 612. And, the cooling medium tube upstreamportion 711 of each cooling medium tube 71 forming the downstream sidecooling medium tube group 70 b is disposed on the downstream side in theflow direction A of the outside air with respect to the cooling mediumtube downstream portion 712.

In the operating state in which the refrigerant introduced into theoutdoor heat exchanging portion 60 and the cooling medium introducedinto the radiator 70 have the temperature higher than that of theoutside air, the heat contained in the refrigerant and the coolant canbe sufficiently dissipated into outside air on the refrigerantdownstream side of the downstream side refrigerant tube group 60 b andon the coolant downstream side of the downstream side cooling mediumtube group 70 b. As a result, the performance of the heat exchanger 16can be improved.

As can be seen from the above description, the upstream side refrigeranttube group 60 a of this embodiment corresponds to an upstream side firsttube group described in the accompanying claims. The downstream siderefrigerant tube 60 b of this embodiment corresponds to a downstreamside first tube group. The upstream side cooling medium tube group 70 aof this embodiment corresponds to an upstream side second tube groupdescribed in the claims. The downstream side cooling medium tube 70 b ofthis embodiment corresponds to a downstream side second tube group.

Other Embodiments

The present invention is not limited to the above embodiments, andvarious modifications and changes can be made to the disclosedembodiments without departing from the scope of the invention.

(1) In the above embodiments, the heat exchanger 16 has the tank andtube heat exchanger structure including two heat exchanging portions 60and 70 with the tubes (61, 71) and the collection and distribution tanks(62, 72), by way of example. The structure of each of the heatexchanging portions 60 and 70 is not limited thereto.

Alternatively, for example, the heat exchanger may employ a so-calleddrawn cup heat exchanger structure including lamination of a pluralityof sheets of plates via the outer fins 50. Each plate includes a tubeand a tank in communication with the tube which are formed by bonding apair of plate members with the respective centers aligned with eachother.

In such a drawn cup heat exchanger structure, the plates are laminatedto communicate the tanks of the plates with each other, which can formthe structure corresponding to each of the refrigerant side header tank62 and the cooling medium side header tank 72 described in the aboveembodiments.

(2) In the above embodiments, the plates 63 and 73 are coupled to thetanks 64 and 74, respectively, which partitions the internal spaces intothe collection spaces 62 a and 72 a, and the distribution spaces 62 band 72 b to thereby form the refrigerant side header tank 62 and thecooling medium side header tank 72, by way of example. The structures ofthe header tanks 62 and 72 are not limited thereto.

For example, the header tank may be composed of two pipes, and theinternal space of each pipe may be a collection space or a distributionspace. This can improve the resistance to pressure of each header tank.

(3) In the above embodiments, the refrigerant tubes 61 and the coolingmedium tubes 71 are alternately laminated or stacked, by way of example.However, the arrangement of the refrigerant tubes 61 and the coolingmedium tubes 71 is not limited thereto.

For example, in the heat exchanger 16 of the first and thirdembodiments, as shown in FIG. 19( a), a plurality of (N pieces of)refrigerant tubes 61 may be continuously laminated, and then a pluralityof (M pieces of) cooling medium tubes 71 may be continuously laminated.At this time, the number of the cooling tubes 61 may be equal ordifferent to that of the cooling medium tubes 71 continuously laminatedthereon.

For example, in the heat exchanger 16 of the second embodiment, as shownin FIGS. 19( b) to 19(d), the refrigerant tubes 61 may be positioned onthe upstream side with respect to the flow direction A of the outsideair, while the cooling medium tubes 71 may be positioned on thedownstream side.

FIGS. 19( a) to 19(d) schematically show the cross-sectional views ofthe header tank of the heat exchanger 16 in the longitudinal direction.In FIGS. 19( a) to 19(d), for easy understanding, the refrigerant tubes61 are indicated by hatching with shaded areas, and the cooling mediumtubes 71 are indicated by dotted hatching.

In the arrangement including the refrigerant tubes 61 placed adjacent toeach other, or the cooling medium tubes 71 placed adjacent to each otheras shown in FIGS. 19( a) to 19(d), the outer fins 50 may be desirablydisposed in a space between the adjacent refrigerant tubes 61, andbetween the adjacent cooling medium tubes 71.

In this way, the outer fins 50 are disposed in all spaces formed betweeneach of the tubes 61 and 71, and the adjacent refrigerant tube 61 orcooling medium tube 71. Thus, the outer fins 50 promote the heatexchange between the outside air and the fluid (refrigerant or coolant)flowing through the tubes 61 and 71, and can relieve (reduce) adifference in thermal strain between the refrigerant tube 61 and thecooling medium tube 71. As a result, the breakdown of the heat exchanger16 can be suppressed.

(4) In the above first embodiment, the cooling medium tube upstreamportion 711 of the cooling medium tube 71 among the refrigerant tubes 61and the cooling medium tubes 71 is positioned on the upstream side inthe flow direction A of the outside air with respect to the coolingmedium tube downstream portion 712, by way of example, which does notlimit the invention.

For example, the refrigerant tube upstream portion 611 of therefrigerant tubes 61 among the refrigerant tubes 61 and the coolingmedium tubes 71 may be positioned on the upstream side in the flowdirection A of the outside air with respect to the refrigerant tubedownstream portion 612.

In the operating state in which the refrigerant introduced into theoutdoor heat exchanging portion 60 has the temperature higher than thatof each of the cooling medium and the outside air, a difference intemperature between the refrigerant and the outside air can be ensuredon the upstream side of the refrigerant flow of the refrigerant tubes 61to increase the amount of heat dissipation. Thus, the difference intemperature between the refrigerant and coolant can be reduced, whichcan release the difference in thermal strain between the refrigeranttubes 61 and the cooling medium tubes 71. In this example, therefrigerant corresponds to a “high-temperature side fluid”; therefrigerant tube 61 to a “high-temperature side tube”; the refrigeranttube upstream portion 611 of the refrigerant tube 61 to a“high-temperature side tube upstream portion”; and the refrigerant tubedownstream portion 12 of the refrigerant tube 61 to a “high-temperatureside tube downstream portion”. The coolant corresponds to a“low-temperature side fluid”; the cooling medium tube 71 to a“low-temperature side tube”; the cooling medium tube upstream portion711 of the cooling medium tube 71 to a “low-temperature side tubeupstream portion”; and the cooling medium tube downstream portion 712 ofthe cooling medium tube 71 to a “low-temperature side tube downstreamportion”.

(5) In the above first embodiment, the refrigerant tube upstreamportions 611 of the refrigerant tubes 61 and the cooling medium tubedownstream portions 712 of the cooling medium tubes 71 are arranged inthe lamination direction of the tubes 61 and 71. And the refrigeranttube downstream portions 612 and the cooling medium tube upstreamportions 711 are arranged in the lamination direction of the tubes 61and 71, by way of example. The invention is not limited to the abovearrangement.

For example, the refrigerant tube upstream portions 611 of therefrigerant tubes 61 and the cooling medium tube upstream portions 711of the cooling medium tubes 71 may be arranged in the laminationdirection of the tubes 61 and 71, and the refrigerant tube downstreamportions 612 and the cooling medium tube downstream portions 712 may bearranged in the lamination direction of the tubes 61 and 71.

In such a structure, the refrigerant flowing through the refrigeranttube 61 and the coolant flowing through the cooling medium tube 71 havethe flow directions opposed to each other in the longitudinal directionof the respective tubes 61 and 71, and the same flow direction in theflow direction of outside air (for example, from the windward side tothe leeward side, or the leeward side to the windward side) (which is apartially parallel flow structure).

The heat exchanger 16 with such a structure reduces the heat exchangingcapacity as compared to the heat exchanger 16 of the first embodiment,but can decrease the difference in temperature between the refrigerantflowing through the refrigerant tubes 61 and the cooling medium flowingthrough the cooling medium tubes 71 as a whole.

Referring to FIG. 20, the following will be the reason why thedifference in temperature between the refrigerant flowing through therefrigerant tube 61 and the cooling medium flowing through the coolingmedium tube 71 can be reduced in the heat exchanger 16 with thepartially parallel flow structure. FIG. 20 is an explanatory diagram forexplaining how the difference in structure between various types of heatexchangers affects the difference in temperature between the refrigerantand coolant in each tube. In FIG. 20, a solid line schematicallyindicates a change in temperature of a high-temperature fluid(high-temperature side fluid) of the refrigerant and the coolant(indicating an inflow portion by a black circle and an outflow portionby a black diamond). An alternate long and short dash line schematicallyindicates a change in temperature of a low-temperature fluid(low-temperature side fluid) in the heat exchanger 16 with a partiallyparallel flow structure. An alternate long and two short dashes lineschematically indicates a change in temperature of a low-temperaturefluid in the opposite flow structure (heat exchanger 16 described in thefirst embodiment). The alternate long and short dash line and thealternate long and two short dashes line respectively show the change intemperature on the following conditions. In the operating state in whichthe temperature of the outside air is lower than that of each of therefrigerant and the coolant, an outflow temperature Tl2 of thelow-temperature side fluid flowing from the tube using the heatexchanger 16 with the partially parallel flow structure is identical toan outflow temperature Tl2′ of the low-temperature side fluid flowingfrom the tube using the heat exchanger 16 with the opposite flowstructure.

As mentioned above, the heat exchanger 16 with the partially parallelflow structure has the heat exchanging capacity reduced as compared tothe heat exchanger 16 described in the first embodiment. As indicated bythe alternate long and short dash line and the alternate long and twoshort dashes line in FIG. 20, in the heat exchanger 16 with thepartially parallel flow structure, the inflow temperature Tl1 of thelow-temperature side fluid flowing into the tubes becomes higher thanthe inflow temperature Tl1′ of the low-temperature side fluid flowinginto the heat exchanger 16 of the first embodiment.

That is, the difference in temperature ΔT between the inflow temperatureTh1 of the high-temperature side fluid and the inflow temperature Tl1 ofthe low-temperature side fluid flowing into the heat exchanger 16 withthe partially parallel flow structure is small as compared to thedifference in temperature ΔT′ between the inflow temperature Tl1 of thehigh-temperature side fluid and the inflow temperature Tl1′ of thelow-temperature side fluid flowing into the heat exchanger 16 of thefirst embodiment.

Thus, the heat exchanger 16 with the partially parallel flow structurecan reduce the difference in temperature between the refrigerant flowingthrough the refrigerant tube 61 and the cooling medium flowing throughthe cooling medium tube 71 as a whole, as compared to the heat exchanger16 of the first embodiment. As a result, the heat exchanger can relievethe difference in thermal strain between the refrigerant tube 61 and thecooling medium tube 71. This embodiment is applied to the operatingstate in which the temperature of the outside air is lower than that ofeach of the refrigerant and coolant, but the heat exchanger 16 with thepartially parallel flow structure can have the following effectregardless of the relationship between the temperature of outside airand that of refrigerant and coolant. That is, the heat exchanger 16 withthe partially parallel flow structure can reduce the difference intemperature between the refrigerant flowing through the refrigerant tube61 and the cooling medium flowing through the cooking medium tube 71 asa whole as compared to the heat exchanger 16 of the first embodiment.

Further, in the heat exchanger 16 with the partially parallel flowstructure, the refrigerant tube upstream portion 611 and the coolingmedium tube upstream portion 711 are desirably positioned on theupstream side in the flow direction of the outside air with respect tothe refrigerant tube downstream portion 612 and the cooling medium tubedownstream portion 712.

In the operating state in which the refrigerant introduced into theoutdoor heat exchanging portion 60 and the cooling medium introducedinto the radiator 70 have the temperature higher than that of theoutside air, the heat exchanger can ensure the differences intemperature between the refrigerant and the outside air, and between thecoolant and the outside air to thereby increase the amount of heatdissipation. As a result, the difference in thermal strain between therefrigerant tube 61 and the cooling medium tube 71 can be relieved tosuppress the breakdown of the heat exchanger 16.

(6) In the above first embodiment, the refrigerant of the heat pumpcycle 10 is used as the first fluid, the coolant of the coolantcirculation circuit 40 is used as the second fluid, and the outside airblown by the blower fan 17 is used as the third fluid, but the first tothird fluids are not limited thereto. For example, like the thirdembodiment, the air in the vehicle interior may be used as the thirdfluid.

For example, the first fluid may be a high-pressure side refrigerant ora low-pressure side refrigerant in the heat pump cycle 10.

For example, the second fluid may be a coolant for cooling electricdevices, such as an engine or an inverter for supplying electric powerto an electric motor MG for traveling. Alternatively, the second fluidmay be oil for cooling, the second heat exchanging portion may serve asan oil cooler, and the second fluid for use may be a heat storage agent,a cooling storage agent, or the like.

The first to third fluids are not limited to fluids whose properties orcomponents are different from each other. The first to third fluids maybe fluids which differ in temperature or state, such as a gas phase or aliquid phase even when those fluids have the same properties orcomponents. For example, the first fluid for use may be a high-pressureside refrigerant in the heat pump cycle 10, and the second fluid for usemay be a low-pressure side refrigerant in the heat pump cycle 10. Forexample, when the heat exchanger is provided with different circuitsadapted for circulating the coolant for cooling the engine and forcirculating the coolant for cooling the invertor, the first fluid foruse is a coolant for the engine, and the second fluid for use is acoolant for the inverter.

The relationship between the temperatures of the first to third fluidsis desirably as follows: the temperature of the third fluid is lowerthan that of one of the first and second fluids having a highertemperature (high-temperature side fluid), and higher than that of theother having a lower temperature (low-temperature side fluid). Such atemperature relationship decreases the temperature of thehigh-temperature side fluid and increases the temperature of thelow-temperature side fluid in the heat exchanger 16, which can decreasethe difference in temperature between the first fluid and the secondfluid. As a result, the difference in thermal strain between the tubes61 and 71 can be relieved to thereby effectively suppress the breakdownof the heat exchanger 16.

When the heat pump cycle 10 to which the heat exchanger 16 of theinvention is applied is used in a stationary air conditioner, a coolingstorage cabinet, a cooling and heating device for a vending machine, orthe like, the second fluid may be a coolant for cooling the engine andelectric motor which serve as a driving source of the compressor of theheat pump cycle 10, as well as other electric devices.

In the above embodiments, the heat exchanger 16 of the invention isapplied to the heat pump cycle (refrigeration cycle), by way of example.The applications of the heat exchanger 16 of the invention are notlimited thereto. That is, the heat exchanger 16 of the invention can bewidely applied to any devices for exchanging heat among three kinds offluids and the like.

(7) In the above embodiments, the refrigerant tubes 61 of the outdoorheat exchanging portion 60, the cooling medium tubes 71 of the radiator70, and the outer fins 50 are formed of an aluminum alloy (metal) andbrazed together, by way of example. The outer fin 50 may be formed ofmaterial with excellent heat conductivity (for example, carbon nanotube,or the like), and may be bonded by any bonding means, such as adhesiveor the like.

FIG. 21 schematically shows a partial perspective view of a heatexchanger 16 according to another embodiment. FIGS. 22( a), 22(b), and22(c) are explanatory diagrams for explaining an outer fin 50 in anotherembodiment. FIG. 22( a) is a partial front view of the outer fin 50,FIG. 22( b) is a cross-sectional view taken along the line XXIIB-XXIIBof FIG. 22( a), and FIG. 22( c) is an enlarged view of an XXIIC part ofFIG. 22( a).

When the outer fin 50 is bonded with the tubes 61 and 71 like the aboverespective embodiments, as shown in FIGS. 21, 22(a), 22(b), and 22(c),the outer fin 50 is desirably provided with a plurality of slits 50 afor locally weakening the rigidity of the outer fin 50. The slit 50 acan be formed of a through hole penetrating the outer fin 50, or acutout formed at the peripheral edge of the outer fin 50.

Thus, each slit 50 a of the outer fin 50 can absorb the stress acting onthe tubes 61 and 71 when there is the difference in thermal strainbetween the tubes 61 and 71. Further, the outer fins 50 with the slits50 a can suppress the breakdown of the heat exchanger 16 within apartial range when the difference in thermal strain between the tubes 61and 71 occurs.

(8) In the above first embodiment, in the tube and tank temporary fixingstep, the refrigerant tubes 61 and the cooling medium tubes 71 aretemporarily fixed together with the inner fins 65 and 75 stuck in theplates 61 a, 61 b, 71 a, and 71 b, by way of example. Alternatively, theplates 61 a, 61 b, 71 a, and 71 b may be provided with positioningportions for the inner fins 65 and 75.

Such positioning portions may be formed of protrusions that protrudeinward, for example, from the refrigerant flow path 61 c, the coolingmedium flow path 71 c, the turning portions 61 e and 71 e, and theenlarging portions 61 f and 71 f.

(9) The above second and third embodiments do not describe the innerfins 65 and 75 disposed inside the refrigerant tubes 61 and the coolingmedium tubes 71. However, when the inner fins 65 and 75 are intended tobe employed, the flat tubes are bent, and then the fins are desirablyinserted into fluid flow paths on the upstream side and the downstreamside of each of the turning portions 61 e and 71 e. Thus, the inner finscan be prevented from being deformed upon bending the flat tube.

(10) In the above embodiments, the electric three-way valve 42 isemployed as circuit switching means for switching among the coolingmedium circuits of the coolant circulation circuit 40, by way ofexample. However, the circuit switching means is not limited thereto.For example, a thermostatic valve may be employed. The thermostaticvalve is a cooling medium temperature responsive valve composed of amechanical system that is designed to open and close a cooling mediumpassage by displacing a valve body by use of a thermowax (temperaturesensing member) whose volume is changed depending on the temperature.Thus, the thermostatic valve can be used to remove the coolanttemperature sensor 52.

(11) Although in the above embodiments, the refrigerant for use is thenormal flon-based refrigerant by way of example, the kind of therefrigerant is not limited thereto. The refrigerant for use may benatural refrigerant, such as carbon dioxide, or a hydrocarbon-basedrefrigerant. Further, the heat pump cycle 10 may be a supercriticalrefrigeration cycle in which the pressure of refrigerant discharged fromthe compressor 11 is equal to or higher than the critical pressure ofthe refrigerant.

The present invention has been disclosed with reference to the preferredembodiments. However, it is to be understood that the present inventionis not limited to the above preferred embodiments and the structuresdescribed above.

The present invention is intended to cover various modified examples andequivalent arrangements thereto. In addition, other preferredembodiments which includes one additional element or which loses oneelement with respect to the disclosed embodiments, or various othercombinations of the embodiments also fall within the scope and spirit ofthe present invention.

1. A heat exchanger comprising: a first heat exchanging portionincluding a plurality of first tubes through which a first fluid flows,and a first tank extending in a direction of lamination of the firsttubes to collect or distribute the first fluid flowing through the firsttubes, the first heat exchanging portion being adapted to exchange heatbetween the first fluid and a third fluid flowing around the firsttubes; and a second heat exchanging portion including a plurality ofsecond tubes through which a second fluid flows, and a second tankextending in a direction of lamination of the second tubes to collect ordistribute the second fluid flowing through the second tubes, the secondheat exchanging portion being adapted to exchange heat between thesecond fluid and the third fluid flowing around the second tubes,wherein the first tubes and the second tubes are disposed between thefirst tank and the second tank, at least one of the first tubes isdisposed between the second tubes, at least one of the second tubes isdisposed between the first tubes, a space formed between the first tubeand the second tube defines a third fluid passage through which thethird fluid flows, an outer fin is disposed in the third fluid passage,to promote heat exchange between both the heat exchanging portions whileenabling heat transfer between the first fluid flowing through the firsttubes and the second fluid flowing through the second tubes, the firsttube is provided with a first turning portion for changing a flowdirection of the first fluid, the second tube is provided with a secondturning portion for changing a flow direction of the second fluid, thefirst turning portion is positioned closer to the second tank than thefirst tank, and the second turning portion is positioned closer to thefirst tank than the second tank.
 2. The heat exchanger according toclaim 1, wherein a temperature of the first fluid introduced into thefirst heat exchanging portion is different from a temperature of thesecond fluid introduced into the second heat exchanging portion, and theouter fin is disposed in a space formed between the first and secondtubes adjacent to each other, between the adjacent first tubes, andbetween adjacent second tubes.
 3. The heat exchanger according to claim1, wherein the first tube and the second tube are fixed to both thefirst tank and the second tank.
 4. The heat exchanger according to claim1, wherein when one fluid with a higher temperature, of the first fluidintroduced into the first heat exchanging portion and the second fluidintroduced into the second heat exchanging portion is defined as ahigh-temperature side fluid, when an upstream side portion of ahigh-temperature side tube of the first tube and the second tube throughwhich the high-temperature fluid flows with respect to a correspondingone of the first and second turning portions is defined as ahigh-temperature side tube upstream portion, and when a downstream sideportion of the high-temperature side tube of the first tube and thesecond tube through which the high-temperature fluid flows with respectto the corresponding one of the first and second turning portions isdefined as a high-temperature side tube downstream portion, thetemperature of the third fluid is lower than that of thehigh-temperature side fluid, and the high-temperature side tube upstreamportion of at least one of the high-temperature side tubes is positionedon an upstream side in a flow direction of the third fluid with respectto the high-temperature side tube downstream portion.
 5. The heatexchanger according to claim 4, wherein when one fluid having a lowertemperature, of the first fluid introduced into the first heatexchanging portion and the second fluid introduced into the second heatexchanging portion is defined as a low-temperature side fluid, when anupstream side portion of a low-temperature side tube of the first tubeand the second tube through which the low-temperature side fluid flowswith respect to a corresponding one of the first and second turningportions is defined as a low-temperature side tube upstream portion, andwhen a downstream side portion of the low-temperature side tube of thefirst tube and the second tube through which the low-temperature fluidflows with respect to the corresponding one of the first and secondturning portions is defined as a low-temperature side tube downstreamportion, the temperature of the third fluid is lower than that of thelow-temperature side fluid, and the low-temperature side tube upstreamportion of at least one of the low-temperature side tubes is positionedon the upstream side in the flow direction of the third fluid withrespect to the low-temperature side tube downstream portion.
 6. The heatexchanger according to claim 1, wherein the temperature of the thirdfluid is lower than that of one fluid having a higher temperature, ofthe first fluid introduced into the first heat exchanging portion andthe second fluid introduced into the second heat exchanging portion, andis higher than that of the other fluid having a lower temperature. 7.The heat exchanger according to claim 1, wherein when an upstream sideportion of the first tube with respect to the first turning portion isdefined as a first tube upstream portion, when a downstream side portionof the first tube with respect to the first turning portion is definedas a first tube downstream portion, when an upstream side portion of thesecond tube with respect to the second turning portion is defined as asecond tube upstream portion, and when a downstream side portion of thesecond tube with respect to the second turning portion is defined as asecond tube downstream portion, the first tube upstream portion and thesecond tube upstream portion are arranged in a direction of laminationof the first and second tubes, and the first tube downstream portion andthe second tube downstream portion are arranged in the direction oflamination of the first and second tubes.
 8. The heat exchangeraccording to claim 7, wherein the first tube upstream portion and thesecond tube upstream portion are positioned on the upstream side in theflow direction of the third fluid with respect to the first tubedownstream portion and the second tube downstream portion.
 9. The heatexchanger according to claim 7, wherein the first tubes include anupstream side first tube group in which the first fluid introduced intothe first heat exchanging portion flows, and a downstream side firsttube group in which the first fluid flowing from the upstream side firsttube group flows to cause the first fluid to flow out the first heatexchanging portion, the second tubes include an upstream side secondtube group in which the second fluid introduced into the second heatexchanging portion flows, and a downstream side second tube group inwhich the second fluid flowing from the upstream side second tube groupflows to cause the second fluid to flow out the second heat exchangingportion, and the first tube upstream portion and the second tubeupstream portion of the upstream side first tube group and the upstreamside second tube group are positioned on the upstream side in the flowdirection of the third fluid with respect to the first tube downstreamportion and the second tube downstream portion.
 10. The heat exchangeraccording to claim 9, wherein the first tube upstream portion and thesecond tube upstream portion of the downstream side first tube group andthe downstream side second tube group are positioned on the downstreamside in the flow direction of the third fluid with respect to the firsttube downstream portion and the second tube downstream portion.
 11. Theheat exchanger according to claim 1, wherein the outer fin is coupled tothe first and second tubes, and provided with a plurality of slits forlocally weakening rigidity of the outer fin.
 12. The heat exchangeraccording to claim 1, wherein an area of a refrigerant passage of anintermediate part of at least one of the first turning portion and thesecond turning portion is larger than an area of a fluid passage of eachof a fluid inflow portion and a fluid outflow portion of the one turningportion.
 13. The heat exchanger according to claim 1, further comprisingan inner fin disposed within at least one of the first tube and thesecond tube, to promote the heat exchange between the first fluid or thesecond fluid, and the third fluid, wherein the inner fin has an endprotruding into an internal space of the first turning portion or secondturning portion.
 14. The heat exchanger according to claim 1, whereineach of the first tube and the second tube is made of a plate tubeformed by bonding a pair of plates.
 15. The heat exchanger according toclaim 1, wherein each of the first tube and the second tube is formed bybending a flat tube with a flat section in a direction perpendicular tothe longitudinal direction of the tube.